clk: imx: fix composite peripheral flags

According to RM, for peripheral clock slice,
"IP clock slices must be stopped to change the clock source.".

So we must have CLK_SET_PARENT_GATE flag to avoid glitch.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>