Fix minimum image size for cl_ext_image_requirements_info

Some new extension formats require the width to be a multiple
of 4 or 2 (see cl_ext_image_raw10_raw12).
Change has not functional impact as the affected image is only used
for generic queries.

Signed-off-by: John Kesapides <john.kesapides@arm.com>

test_conformance/images/kernel_read_write/test_cl_ext_image_buffer.hpp

@@ -48,8 +48,10 @@ static inline size_t get_format_size(cl_context context,
     cl_image_desc image_desc = { 0 };
     image_desc.image_type = imageType;
 
-    /* Size 1 only to query element size */
-    image_desc.image_width = 1;
+    /* We use a width of 4 to query element size, as this is
+       the smallest possible value that satisfies the requirements 
+       of all image formats (including extensions). */
+    image_desc.image_width = 4;
     if (CL_MEM_OBJECT_IMAGE1D_BUFFER != imageType
         && CL_MEM_OBJECT_IMAGE1D != imageType)
     {