radeonsi: use level mask for early out in si_blit_decompress_color
radeonsi: use level mask for early out in si_blit_decompress_color

Mostly for consistency with the other decompress functions, but note that
in the non-DCC decompress case, the function can now early-out in slightly
more (albeit probably rare) cases.

Reviewed-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler