clk: sunxi-ng: a64: Allow parent change for VE clock

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>