vrend: correct blit/copy_image code path
Gallium copy_image redirects calls to resource_copy_region for equal src and dst formats or if at least one of the two is compressed. Handle the condition for selecting blit vs. glCopyImageSubRegion accordingly.
Fixes piglit: bptc-float-modes
Signed-off-by: Gert Wollny gert.wollny@collabora.com