clk: imx: scu: add parallel port clock ops

Because digital pll for parallel interface is on by default, and
not provide enable/disable function by scu, so add the related ops
for this kind of clocks.

Signed-off-by: Guoniu.zhou <guoniu.zhou@nxp.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>