Video PLLs need to be referenced in R40 DT as possible HDMI PHY parent.

Export them.
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>