imx: add i.MX8 SoCs OTP SIP(silicon provider) service support

For NXP's i.MX8 SoCs with system controller inside, OTP is
maintained by SCFW, Linux needs to call SMC to trap to TF-A
for OTP read/write etc. operations by calling SCFW API.

This patch adds OTP SIP service support.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
diff --git a/plat/imx/common/include/imx_sip_svc.h b/plat/imx/common/include/imx_sip_svc.h
index 4de2194..3fa6b82 100644
--- a/plat/imx/common/include/imx_sip_svc.h
+++ b/plat/imx/common/include/imx_sip_svc.h
@@ -18,6 +18,9 @@
 #define IMX_SIP_WAKEUP_SRC_SCU		0x1
 #define IMX_SIP_WAKEUP_SRC_IRQSTEER	0x2
 
+#define IMX_SIP_OTP_READ		0xC200000A
+#define IMX_SIP_OTP_WRITE		0xC200000B
+
 #if (defined(PLAT_IMX8QM) || defined(PLAT_IMX8QX))
 int imx_cpufreq_handler(uint32_t smc_fid, u_register_t x1,
 			u_register_t x2, u_register_t x3);
@@ -25,6 +28,8 @@
 		     u_register_t x2, u_register_t x3, u_register_t x4);
 int imx_wakeup_src_handler(uint32_t smc_fid, u_register_t x1,
 			   u_register_t x2, u_register_t x3);
+int imx_otp_handler(uint32_t smc_fid, void *handle,
+		    u_register_t x1, u_register_t x2);
 #endif
 
 #endif /* __IMX_SIP_SVC_H__ */