backend/drm: commit/rollback FBs in drm_crtc_commit
backend/drm: commit/rollback FBs in drm_crtc_commit

We need to perform the FB bookkeeping on all commits, not just on
page-flips.

swaywm/wlroots,swaywm/wlroots,ascent12/wlroots,ascent12/wlroots,SirCmpwn/wlroots