drm/vc4: hdmi: Move XBAR setup to csc_setup

On the BCM2711, the HDMI_VEC_INTERFACE_XBAR register configuration
depends on whether we're using an RGB or YUV output. Let's move that
configuration to the CSC setup.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>