compositor-drm: Release the correct buffer in drm_output_release_fb
compositor-drm: Release the correct buffer in drm_output_release_fb

eyolfson/weston,Gnurou/weston,mchalupa/weston,sir-murray/weston,sir-murray/weston,Fantu/compositor-spice,Fantu/compositor-spice,Gnurou/weston,giucam/weston,udoprog/weston,kwm81/weston,Fantu/compositor-spice,xorgy/weston,eyolfson/weston,jonnylamb/weston,udoprog/weston,krezovic/weston,jonnylamb/weston,kwm81/weston,Tarnyko/weston-xdg_surface_present,Tarnyko/weston-xdg_surface_present,xorgy/weston,mchalupa/weston,krezovic/weston,giucam/weston