rpi-backend: ensure pixels is destroyed in resource_update
rpi-backend: ensure pixels is destroyed in resource_update

Signed-off-by: U. Artie Eoff <32aece0d55055227b44d04b7d0051cf3d04ee871@intel.com>

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