shell: fix positioning of maximized surfaces with a custom geometry
shell: fix positioning of maximized surfaces with a custom geometry

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