tgsi: update PK2H/UP2H channel behavior info
tgsi: update PK2H/UP2H channel behavior info

Signed-off-by: Ilia Mirkin <bcbbb7aa705ec3a5fc5824c01a845186c3d62fca@alum.mit.edu>
Reviewed-by: Edward O'Callaghan <117173807d5a49976a891944633465c0daea7f98@alterapraxis.com>
Reviewed-by: Roland Scheidegger <7d58aee419d6f9201d75517c885374dff5e7d848@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler