IVGCVSW-3236 Extend Ref LSTM with layer normalization support

* Add descriptor values
* Update lstm queue descriptor validate function
* Update lstm workload
* Update isLstmSupported (Cl and Ref), LayerSupportBase, ILayerSupport
* Update lstm layer
* Add unit tests

Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Change-Id: I932175d550facfb342325051eaa7bd2084ebdc18
Signed-off-by: Jan Eilers <jan.eilers@arm.com>
diff --git a/src/backends/reference/backend.mk b/src/backends/reference/backend.mk
index 12e5774..a736a88 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -22,6 +22,7 @@
         workloads/ElementwiseFunction.cpp \
         workloads/FullyConnected.cpp \
         workloads/Gather.cpp \
+        workloads/LstmUtils.cpp \
         workloads/Mean.cpp \
         workloads/Concatenate.cpp \
         workloads/Pad.cpp \