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/include/asm/arch-imx8m/clock.h b/arch/arm/include/asm/arch-imx8m/clock.h
index dded6e0..c910b61 100644
--- a/arch/arm/include/asm/arch-imx8m/clock.h
+++ b/arch/arm/include/asm/arch-imx8m/clock.h
@@ -9,7 +9,7 @@
 
 #ifdef CONFIG_IMX8MQ
 #include <asm/arch/clock_imx8mq.h>
-#elif defined(CONFIG_IMX8MM)
+#elif defined(CONFIG_IMX8MM) || defined(CONFIG_IMX8MN)
 #include <asm/arch/clock_imx8mm.h>
 #else
 #error "Error no clock.h"