rpi: remove weston_plane support
rpi: remove weston_plane support

There is no need to support weston_plane anymore.
The max-planes option is removed as unused.

Signed-off-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>

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