IVGCVSW-4516 Add ConvertFp32ToBf16Layer and Ref workload support

Signed-off-by: Narumol Prangnawarat <narumol.prangnawarat@arm.com>
Change-Id: I9099a4f840fb747336f77d20a0868b64e801a310
diff --git a/src/backends/reference/backend.mk b/src/backends/reference/backend.mk
index aeac2e2..239863f 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -51,6 +51,7 @@
         workloads/RefConstantWorkload.cpp \
         workloads/RefConvertBf16ToFp32Workload.cpp \
         workloads/RefConvertFp16ToFp32Workload.cpp \
+        workloads/RefConvertFp32ToBf16Workload.cpp \
         workloads/RefConvertFp32ToFp16Workload.cpp \
         workloads/RefConvolution2dWorkload.cpp \
         workloads/RefDebugWorkload.cpp \