Cedrus driver wants to set VE clock higher than it's possible without
changing parent rate.

Allow changing parent rate for VE clock, so clock rate can be set
freely.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>