nvc0/ir: check that the image format doesn't mismatch

nvc0/ir: check that the image format doesn't mismatch

This re-uses NVE4_SU_INFO_CALL which is not used anymore because we
don't use our lib for format conversions. While we are at it, add a
todo for image buffers because there are some robustness-related
issues to fix.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>