drm/rockchip: vop2: disable planes when disabling the crtc

The vop2 driver needs to explicitly disable the planes if the crtc is
disabled. Unless the planes are explicitly disabled, the address of the
last framebuffer is kept in the registers of the VOP2. When re-enabling
the encoder after it has been disabled by the driver, the VOP2 will
start and read the framebuffer that has been freed but is still pointed
to by the register. The iommu will catch these read accesses and print
errors.

Explicitly disable the planes when the crtc is disabled to reset the
registers.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221028095206.2136601-3-m.tretter@pengutronix.de