COMPMID-920: Introduce prepare() stage

Change-Id: I08ddb7f6e061178e7566518b48e4e18f8f078596
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/129825
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
diff --git a/arm_compute/runtime/CL/functions/CLGEMMConvolutionLayer.h b/arm_compute/runtime/CL/functions/CLGEMMConvolutionLayer.h
index a24ac3a..3dde529 100644
--- a/arm_compute/runtime/CL/functions/CLGEMMConvolutionLayer.h
+++ b/arm_compute/runtime/CL/functions/CLGEMMConvolutionLayer.h
@@ -153,6 +153,7 @@
 
     // Inherited methods overridden:
     void run() override;
+    void prepare() override;
 
 private:
     /** Configures the appropriate matrix multiply routine
@@ -192,8 +193,8 @@
     CLTensor _tmp_output;
 
     bool _is_quantized;
-    bool _is_first_run;
     bool _is_activationlayer_enabled;
+    bool _is_prepared;
 };
 }
 #endif /* __ARM_COMPUTE_CLGEMMCONVOLUTIONLAYER_H__ */