clk: imx7d: reset parent for mipi csi root

To guarantee that we do not get Overflow in image FIFO the outer bandwidth has
to be faster than inputer bandwidth. For that it must be possible to set a
faster frequency clock. So set new parent to sys_pfd3 clock for the mipi csi
block.

Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>