drm/atomic: Improve debug messages

Print the id/name of the object we're dealing with. Makes it easier to
figure out what's going on. Also toss in a few extra debug prints that
might be useful.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180611193403.16118-1-ville.syrjala@linux.intel.com
Reviewed-by: Harry Wentland <harry.wentland@amd.com>