drm/sun4i: Fix component unbinding and component master deletion

For our component-backed driver to be properly removed, we need to
delete the component master in sun4i_drv_remove and make sure to call
component_unbind_all in the master's unbind so that all components are
unbound when the master is.

Fixes: 9026e0d1

 ("drm: Add Allwinner A10 Display Engine support")
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190418132727.5128-4-paul.kocialkowski@bootlin.com