drm/panel: p079zca: unconditionally remove the panel on removal

There is no need to check innolux->base.dev when trying to remove
the panel, as that variable is always set directly before the panel
gets added and will still be available on panel_remove.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180816140920.5009-1-heiko@sntech.de