drm/i915: Extract skl_universal_plane_init()

drm/i915: Extract skl_universal_plane_init()

There's not much point in following the primary vs. sprite split
for the SKL+ universal plane init code. The only difference is
of our own doing in the form of the .check_plane(). Let's make
a small exception for that little detail and otherwise share
the same code to initialize all the universal planes.

Eventually we should eliminate the mess around .check_plane()
as well, but for now let's be happy with some code reduction.

v2: Remember to set up plane->has_fbc
    Make skl_plane_has_ccs() static
v3: Rebase due to NV12, rename some variables
v4: Don't leave the color_encoding/range props behind
v5: Rebase dur to blend properties, skl_plane_max_stride() and
    skl_plane_check()
v6: Make skl_update_plane() static

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> #v4
Link: https://patchwork.freedesktop.org/patch/msgid/20181005125817.22576-10-ville.syrjala@linux.intel.com