drm/rockchip: analogix_dp: reorder psr_unregister call in unbind

drm/rockchip: analogix_dp: reorder psr_unregister call in unbind

In bind the psr handler gets registered first before the core
analogix_dp_bind() gets called. So it should be the other way
around in unbind, first unbind the analogix_dp and then
unregister the psr.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/76025075.yWNtk1v57f@phil