clk: sunxi-ng: a33: Add CLK_SET_RATE_PARENT to ac-dig

The audio DAI needs to set the clock rates of the ac-dig clock.
To make it possible, the parent PLL audio clock rates should
also be changed. This is possible via "CLK_SET_RATE_PARENT" flag.

Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>