imx8m: add clk support for i.MX8MN

i.MX8MN has similar architecture with i.MX8MM, so it could reuse
the clock code of i.MX8MM, but i.MX8MN has different CCM root
configurations, so need a separate root entry.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx8m/Makefile b/arch/arm/mach-imx/imx8m/Makefile
index 92184f3..db4ba30 100644
--- a/arch/arm/mach-imx/imx8m/Makefile
+++ b/arch/arm/mach-imx/imx8m/Makefile
@@ -5,4 +5,4 @@
 obj-y += lowlevel_init.o
 obj-y += clock_slice.o soc.o
 obj-$(CONFIG_IMX8MQ) += clock_imx8mq.o
-obj-$(CONFIG_IMX8MM) += clock_imx8mm.o
+obj-$(CONFIG_IMX8MM)$(CONFIG_IMX8MN) += clock_imx8mm.o