drm/radeon/kms: add some sanity checks to obj info record parsingi (v2)

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=35502



agd5f: also add sanity check to connector records.

v2: fix one more case.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>