drm/i915: Pimp display fault reporting

Decode the display faults a bit more extensively so that one
doesn't have to translate the bitmask to planes/etc. manually.
Also for plane faults we can read out a bit of state from the
relevant plane(s) and dump that out.

Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250217070047.953-4-ville.syrjala@linux.intel.com