drm: zte: move struct vou_inf into zx_vou driver

Although data in struct vou_inf is defined per output device, it doesn't
belong to the device itself but VOU control module.  All these data can
just be defined in VOU driver, and output device driver only needs to
invoke VOU driver function with device ID to enable/disable specific
output device.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>