MLECO-3070: Further HAL cleanup.

Cleaning up HAL sources by removing unnecessary redirections
with function pointers. The "platform packages" under HAL are
now streamlined enough to not need any major HAL wrapping (as
was the case before).

This allows us to have a very thin HAL layer that sits on top
of the platform and compnent packs. Also helps in getting rid
of "hal platform" pointer being passed around in the code to
use any HAL functionality.

Change-Id: I04b2057f972aad7a5cfb4a396bcdf147c9f9ef1c
Signed-off-by: Kshitij Sisodia <kshitij.sisodia@arm.com>
diff --git a/source/hal/source/components/npu/ethosu_profiler.c b/source/hal/source/components/npu/ethosu_profiler.c
index 3ac3497..5d50b09 100644
--- a/source/hal/source/components/npu/ethosu_profiler.c
+++ b/source/hal/source/components/npu/ethosu_profiler.c
@@ -22,6 +22,8 @@
 
 extern struct ethosu_driver ethosu_drv;     /* Default Arm Ethos-U NPU device driver object */
 static ethosu_pmu_counters npu_counters;    /* NPU counter local instance */
+static const char* unit_beats = "beats";
+static const char* unit_cycles = "cycles";
 
 /**
  * @brief Gets the npu counter instance to be used.
@@ -59,29 +61,29 @@
     counters->npu_evt_counters[0].event_type = ETHOSU_PMU_NPU_IDLE;
     counters->npu_evt_counters[0].event_mask = ETHOSU_PMU_CNT1_Msk;
     counters->npu_evt_counters[0].name = "NPU IDLE";
-    counters->npu_evt_counters[0].unit = "cycles";
+    counters->npu_evt_counters[0].unit = unit_cycles;
 
     counters->npu_evt_counters[1].event_type = ETHOSU_PMU_AXI0_RD_DATA_BEAT_RECEIVED;
     counters->npu_evt_counters[1].event_mask = ETHOSU_PMU_CNT2_Msk;
     counters->npu_evt_counters[1].name = "NPU AXI0_RD_DATA_BEAT_RECEIVED";
-    counters->npu_evt_counters[1].unit = "beats";
+    counters->npu_evt_counters[1].unit = unit_beats;
 
     counters->npu_evt_counters[2].event_type = ETHOSU_PMU_AXI0_WR_DATA_BEAT_WRITTEN;
     counters->npu_evt_counters[2].event_mask = ETHOSU_PMU_CNT3_Msk;
     counters->npu_evt_counters[2].name = "NPU AXI0_WR_DATA_BEAT_WRITTEN";
-    counters->npu_evt_counters[2].unit = "beats";
+    counters->npu_evt_counters[2].unit = unit_beats;
 
     counters->npu_evt_counters[3].event_type = ETHOSU_PMU_AXI1_RD_DATA_BEAT_RECEIVED;
     counters->npu_evt_counters[3].event_mask = ETHOSU_PMU_CNT4_Msk;
     counters->npu_evt_counters[3].name = "NPU AXI1_RD_DATA_BEAT_RECEIVED";
-    counters->npu_evt_counters[3].unit = "beats";
+    counters->npu_evt_counters[3].unit = unit_beats;
 #else /* ETHOSU_PMU_NCOUNTERS >= 4 */
     #error "NPU PMU expects a minimum of 4 available event triggered counters!"
 #endif /* ETHOSU_PMU_NCOUNTERS >= 4 */
 
 #if ETHOSU_DERIVED_NCOUNTERS >= 1
     counters->npu_derived_counters[0].name = "NPU ACTIVE";
-    counters->npu_derived_counters[0].unit = "cycles";
+    counters->npu_derived_counters[0].unit = unit_cycles;
 #endif /* ETHOSU_DERIVED_NCOUNTERS >= 1 */
 
     for (i = 0; i < ETHOSU_PMU_NCOUNTERS; ++i) {
diff --git a/source/hal/source/components/npu/include/ethosu_profiler.h b/source/hal/source/components/npu/include/ethosu_profiler.h
index ca95b19..093c07f 100644
--- a/source/hal/source/components/npu/include/ethosu_profiler.h
+++ b/source/hal/source/components/npu/include/ethosu_profiler.h
@@ -29,14 +29,14 @@
     enum ethosu_pmu_event_type event_type;
     uint32_t event_mask;
     uint32_t counter_value;
-    char* unit;
-    char* name;
+    const char* unit;
+    const char* name;
 } npu_evt_counter;
 
 typedef struct npu_derived_counter_ {
     uint32_t counter_value;
-    char* unit;
-    char* name;
+    const char* unit;
+    const char* name;
 } npu_derived_counter;
 
 typedef struct ethosu_pmu_counters_ {