imx8: add iomux configuration api

Add iomux configuration api.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/mach-imx/imx8/Makefile b/arch/arm/mach-imx/imx8/Makefile
index 5787613..31ad169 100644
--- a/arch/arm/mach-imx/imx8/Makefile
+++ b/arch/arm/mach-imx/imx8/Makefile
@@ -4,4 +4,4 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y += cpu.o
+obj-y += cpu.o iomux.o