imx: add i.MX8M into Kconfig

Add i.MX8M into Kconfig, create a new folder mx8m
dedicated for i.MX8M.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 0e0ae77..5881fdc 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -95,11 +95,11 @@
 libs-y += arch/arm/lib/
 
 ifeq ($(CONFIG_SPL_BUILD),y)
-ifneq (,$(CONFIG_MX23)$(CONFIG_MX28)$(CONFIG_MX35)$(filter $(SOC), mx25 mx5 mx6 mx7 mx35))
+ifneq (,$(CONFIG_MX23)$(CONFIG_MX28)$(CONFIG_MX35)$(filter $(SOC), mx25 mx5 mx6 mx7 mx35 mx8m))
 libs-y += arch/arm/mach-imx/
 endif
 else
-ifneq (,$(filter $(SOC), mx25 mx27 mx5 mx6 mx7 mx7ulp mx31 mx35 mxs vf610))
+ifneq (,$(filter $(SOC), mx25 mx27 mx5 mx6 mx7 mx7ulp mx31 mx35 mxs mx8m vf610))
 libs-y += arch/arm/mach-imx/
 endif
 endif