simple-egl: Clean up unused frame_listener
simple-egl: Clean up unused frame_listener

Unused since commit 1e65840b6103197a684a551925a58fb1ae6c40e3

Signed-off-by: Boyan Ding <53c2f6a61c0fa7f115ecc08b03fdb6b52482ccbc@126.com>
Reviewed-by: Nils Chr. Brause <241f9b9bed2172909aeb12ebeed776ef889f3725@gmail.com>

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