ivi-shell: harden get_ivi_shell_surface()
ivi-shell: harden get_ivi_shell_surface()

Add more sanity checks to get_ivi_shell_surface() just in case.

If the configure hook is set, we must always have non-NULL
configure_private.

Check the ivi_shell_surface matches the surface.

Signed-off-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>
Reviewed-by: Eugen Friedrich <d4422ed1e14343198966fa0f35c3c77077052941@gmail.com>

sir-murray/weston,giucam/weston,krezovic/weston,giucam/weston,sir-murray/weston,krezovic/weston,Gnurou/weston,Gnurou/weston