Add support for CLVK

This patch enables CLVK through the graph API and inside the
CLScheduler. By default the Native platform is selected.
Selecting CLVK can be done via --target=clvk.

Resolves COMPMID-4205 and COMPMID-4206

Change-Id: Ic60744980c6b8a60e776627ea677ed46be88f656
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5475
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
diff --git a/utils/CommonGraphOptions.h b/utils/CommonGraphOptions.h
index 670a307..f2cbd48 100644
--- a/utils/CommonGraphOptions.h
+++ b/utils/CommonGraphOptions.h
@@ -40,7 +40,7 @@
  *
  * --help             : Print the example's help message.
  * --threads          : The number of threads to be used by the example during execution.
- * --target           : Execution target to be used by the examples. Supported target options: Neon, CL.
+ * --target           : Execution target to be used by the examples. Supported target options: Neon, CL, CLVK.
  * --type             : Data type to be used by the examples. Supported data type options: QASYMM8, F16, F32.
  * --layout           : Data layout to be used by the examples. Supported data layout options : NCHW, NHWC.
  * --enable-tuner     : Toggle option to enable the OpenCL dynamic tuner.