drm/i915: Add frontbuffer tracking tracepoints

Add some tracpoints for frontbuffer tracking so we can
try to figure out what's going on.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210414022309.30898-2-ville.syrjala@linux.intel.com


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