drm/i915: Consolidate the intel_plane_(un)pin_fb() implementations

drm/i915: Consolidate the intel_plane_(un)pin_fb() implementations

Currently i915 and xe each implement their own versions of
intel_plane_(un)pin(). Now that we have the fb_pin parent
interface we can consolidate this to a single implementation.

The result is a mixture of the i915 and xe implementations.
The reuse_vma() hack comes from xe (and i915 doesn't implement
that part of the parent interface, and the pin_params are
taken from i915 since the platforms supported by i915 need
more things.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260508143426.26504-17-ville.syrjala@linux.intel.com