Enable march=armv8.6-a in non multi-isa builds

* scons arch=armv8.6-a translates to -march=armv8.6-a
* scons arch=armv8.6-a-sve translates to -march=armv8.6-a+sve
* scons arch=armv8.6-a-sve2 translates to -march=armv8.6-a+sve2
* Resolves COMPMID-5408

Change-Id: I0901e1de864d00109759509af7cc2b5c9ae1cd75
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/7943
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
diff --git a/support/Bfloat16.h b/support/Bfloat16.h
index 173f2d1..5fd45cf 100644
--- a/support/Bfloat16.h
+++ b/support/Bfloat16.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2021 Arm Limited.
+ * Copyright (c) 2020-2022 Arm Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -40,7 +40,7 @@
 inline uint16_t float_to_bf16(const float v)
 {
     const uint32_t *fromptr = reinterpret_cast<const uint32_t *>(&v);
-#if defined(__ARM_FEATURE_BF16_VECTOR_ARITHMETIC) || defined(ARM_COMPUTE_FORCE_BF16)
+#if defined(ARM_COMPUTE_ENABLE_BF16)
     uint16_t res;
 
     __asm __volatile(
@@ -50,7 +50,7 @@
         :
         : [fromptr] "r"(fromptr), [toptr] "r"(&res)
         : "v0", "memory");
-#else  /* defined(__ARM_FEATURE_BF16_VECTOR_ARITHMETIC) || defined(ARM_COMPUTE_FORCE_BF16) */
+#else  /* defined(ARM_COMPUTE_ENABLE_BF16) */
     uint16_t       res   = (*fromptr >> 16);
     const uint16_t error = (*fromptr & 0x0000ffff);
     uint16_t       bf_l  = res & 0x0001;
@@ -58,7 +58,7 @@
     {
         res += 1;
     }
-#endif /* defined(__ARM_FEATURE_BF16_VECTOR_ARITHMETIC) || defined(ARM_COMPUTE_FORCE_BF16) */
+#endif /* defined(ARM_COMPUTE_ENABLE_BF16) */
     return res;
 }