drm/i915: Unify the FB and plane state view information into one struct

To allow the simplification of FB/plane view computation in the
follow-up patches, unify the corresponding state in the
intel_framebuffer and intel_plane_state structs into a new intel_fb_view
struct.

This adds some overhead to intel_framebuffer as the rotated view will
have now space for 4 color planes instead of the required 2 and it'll
also contain the unused offset for each color_plane info. Imo this is an
acceptable trade-off to get a simplified way of the remap computation.

Use the new intel_fb_view struct for the FB normal view as well, so (in
the follow-up patches) we can remove the special casing for normal view
calculation wrt. the calculation of remapped/rotated views. This also
adds an overhead to the intel_framebuffer struct, as the gtt remap info
and per-color plane offset/pitch is not required for the normal view,
but imo this is an acceptable trade-off as above. The per-color plane
pitch filed will be used by a follow-up patch, so we can retrieve the
pitch for each view in the same way.

No functional changes in this patch.

v2:
- Make the patch have _no functional change_.
  (fix skl_check_nv12_aux_surface() and skl_check_main_surface()).
- s/i915_color_plane_view::pitch/stride/ (Ville)

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210325214808.2071517-17-imre.deak@intel.com