st/vdpau: don't return a device if the screen doesn't support NPOT

NV3x cards don't support NPOT textures. Technically this restriction
could be worked around, but since it also doesn't expose any video
decoding hw, just turn it off entirely.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: 10.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
st/vdpau: fix bogus error handling in output/bitmap creation

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Christian König <christian.koenig@amd.com>
st/vdpau: check surface params before creating surfaces

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Christian König <christian.koenig@amd.com>