drm/i915: Do vrr push before sampling the frame counter

Do the vrr push before we sample the frame counter to
know when the commit has been latched. Doing these in the
wrong order could lead us to complete the flip before it
has actually happened.

Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020223339.669-3-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>