radeonsi: assert that the DB format is valid (v2)

radeonsi: assert that the DB format is valid (v2)

Assert that the DB format is valid and default to
the INVALID hw format rather than ~0U when the format
doesn't match for non-debug builds.

v2: use INVALID hw format rather than ~0U

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>