drm/i915: Introduce a minimal plane error state

drm/i915: Introduce a minimal plane error state

I want to capture a little bit more information about the state
of the plane upon faults. To that end introduce a small plane error
state struct and provide per-plane vfuncs to read it out.

For now we just stick the CTL, SURF, and SURFLIVE (if available)
registers contents in there.

v2: Use struct intel_display instead of dev_priv

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/20250217070047.953-3-ville.syrjala@linux.intel.com