drm/i915: Add skl+ plane name aliases to enum plane_id

drm/i915: Add skl+ plane name aliases to enum plane_id

Using PLANE_PRIMARY + PLANE_SPRITE? on skl+ results in a bunch
of unnecessary head scratching. Add aliases using the skl+ plane
names.
And for pre-skl we only need to keep PRIMARY,SPRITE0,SPRITE1
as we only ever have 0-2 sprites per pipe on those platforms.

v2: Don't break icl_nv12_y_plane_mask() (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240517171208.21313-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>