clk: imx: add i.MX8MN ccf driver

Add i.MX8MM ccf driver support.
Modifed from Linux Kernel 5.3.0-rc1, drop some entries
that not used in U-Boot and adapt to U-Boot CCF style.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Lukasz Majewski <lukma@denx.de>
diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
index 5ad7967..222c5a4 100644
--- a/drivers/clk/imx/Makefile
+++ b/drivers/clk/imx/Makefile
@@ -12,3 +12,5 @@
 endif
 obj-$(CONFIG_$(SPL_TPL_)CLK_IMX8MM) += clk-imx8mm.o clk-pll14xx.o \
 				clk-composite-8m.o
+obj-$(CONFIG_$(SPL_TPL_)CLK_IMX8MN) += clk-imx8mn.o clk-pll14xx.o \
+				clk-composite-8m.o