drm/i915: Add async flip tracepoint

Add a separate tracepoint for async flips vs. sync plane updates
to make it a bit easier to figure out what is happening.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240611133344.30673-3-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>