imx: add sip function

Add SiP (Silicon Provider) services function to issue
SMC call to Arm Trusted Firmware.

More SiP information could be found in
  https://github.com/ARM-software/arm-trusted-firmware/blob/master/
  docs/arm-sip-service.rst

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index cf39d08..63db0e1 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -124,6 +124,8 @@
 
 targets += $(addprefix ../../../,$(IMX_CONFIG) SPL u-boot.uim spl/u-boot-nand-spl.imx)
 
+obj-$(CONFIG_ARM64) += sip.o
+
 obj-$(CONFIG_MX5) += mx5/
 obj-$(CONFIG_MX6) += mx6/
 obj-$(CONFIG_MX7) += mx7/