clk: imx: Add support for i.MX8MP clock driver

Add clock driver support for i.MX8MP which is a new SoC of i.MX8M
family.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>