According to RM, Page 574, Chapter 5.2.6.4.3 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>