IVGCVSW-3119 Rename MergerLayer to ConcatLayer

!android-nn-driver:1210

Change-Id: I940b3b9e421c92bfd55ae996f7bc54ac077f2604
Signed-off-by: Jim Flynn <jim.flynn@arm.com>
diff --git a/src/backends/reference/backend.mk b/src/backends/reference/backend.mk
index 1c7f8dc..9a4cf14 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -21,7 +21,7 @@
         workloads/FullyConnected.cpp \
         workloads/Gather.cpp \
         workloads/Mean.cpp \
-        workloads/Merger.cpp \
+        workloads/Concatenate.cpp \
         workloads/Pad.cpp \
         workloads/Pooling2d.cpp \
         workloads/RefActivationWorkload.cpp \