COMPMID-648: Fix initial value for MAX pooling for QS types in CL.

Initial value was set two times for QS type in the generic case in pooling_layer.cl

Change-Id: Iddaad0bb48852388cf5e92d764150404454ac46e
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/93238
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
diff --git a/src/core/CL/cl_kernels/pooling_layer.cl b/src/core/CL/cl_kernels/pooling_layer.cl
index 5304c71..6379c28 100644
--- a/src/core/CL/cl_kernels/pooling_layer.cl
+++ b/src/core/CL/cl_kernels/pooling_layer.cl
@@ -502,7 +502,6 @@
 #define MIN_VAL_EXPAND(type) type##_MIN
 #define MIN_VAL(type) MIN_VAL_EXPAND(type)
 #define INITIAL_VALUE MIN_VAL(DATA_TYPE)
-#define INITIAL_VALUE 0
 #else // FIXED_POINT_POSITION
 #if FP16
 #define INITIAL_VALUE -HALF_MAX