samplerlessReads: Release Image to stop Memory Leak (#984)

A previously created Image was not being released leading to a
memory leak.

Change-Id: I9715b5c4193a8e89c6c182b443959009ce1f1129
Signed-off-by: Chetankumar Mistry <chetan.mistry@arm.com>

test_conformance/images/samplerlessReads/test_read_1D_array.cpp

@@ -173,6 +173,8 @@ int test_read_image_1D_array( cl_context context, cl_command_queue queue, cl_ker
 
     clReleaseSampler(actualSampler);
     clReleaseMemObject(results);
+    clReleaseMemObject(read_only_image);
+
     if(gTestReadWrite)
     {
         clReleaseMemObject(read_write_image);