clk: imx: add clk api for supporting CLK_OPS_PARENT_ENABLE clocks

IMX SoCs like i.MX7D requires using CLK_OPS_PARENT_ENABLE flags,
adding the corresponding clock APIs variants for easily to use.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>