drm: Constify struct drm_info_list * arguments

Those functions are just reading data from those pointers.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --cc drivers/gpu/drm/drm_debugfs.c
Simple merge

diff --cc include/drm/drmP.h
Simple merge