drm/i915: Reuse the async_flip() hook for the async flip disable w/a

drm/i915: Reuse the async_flip() hook for the async flip disable w/a

On some platforms we need to trigger an extra async flip with
the async flip bit disabled, and then wait for the next vblank
until the async flip bit off state will actually latch.

Currently the w/a is just open coded for skl+ universal planes.
Instead of doing that lets reuse the .async_flip() hook for this
purpose since it needs to write the exact same set of registers.
In order to do this we'll just have the caller pass in the state
of the async flip bit explicitly.

Cc: Karthik B S <karthik.b.s@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210111163711.12913-8-ville.syrjala@linux.intel.com
Reviewed-by: Karthik B S <karthik.b.s@intel.com>