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/Kconfig b/drivers/clk/imx/Kconfig
index aae69cf..0ba8bc9 100644
--- a/drivers/clk/imx/Kconfig
+++ b/drivers/clk/imx/Kconfig
@@ -36,3 +36,19 @@
 	select CLK_CCF
 	help
 	  This enables support clock driver for i.MX8MM platforms.
+
+config SPL_CLK_IMX8MN
+	bool "SPL clock support for i.MX8MN"
+	depends on ARCH_IMX8M && SPL
+	select SPL_CLK
+	select SPL_CLK_CCF
+	help
+	  This enables SPL DM/DTS support for clock driver in i.MX8MN
+
+config CLK_IMX8MN
+	bool "Clock support for i.MX8MN"
+	depends on ARCH_IMX8M
+	select CLK
+	select CLK_CCF
+	help
+	  This enables support clock driver for i.MX8MN platforms.