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/include/asm/mach-imx/sys_proto.h b/arch/arm/include/asm/mach-imx/sys_proto.h
index d518e03..c53e540 100644
--- a/arch/arm/include/asm/mach-imx/sys_proto.h
+++ b/arch/arm/include/asm/mach-imx/sys_proto.h
@@ -126,4 +126,7 @@
 int mxs_reset_block(struct mxs_register_32 *reg);
 int mxs_wait_mask_set(struct mxs_register_32 *reg, u32 mask, u32 timeout);
 int mxs_wait_mask_clr(struct mxs_register_32 *reg, u32 mask, u32 timeout);
+
+unsigned long call_imx_sip(unsigned long id, unsigned long reg0,
+			   unsigned long reg1, unsigned long reg2);
 #endif