amlogic: scpi: Add support to retrieve chip ID

Both kernel and U-Boot use a SMC call to the secure monitor to get the
chip ID. This call is translated by BL31 to a call to the SCP to
retrieve the ID. Add a new SiP call and the backing SCPI command.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Change-Id: Ib128f5645ee92866e7ebbcd550dacd33f573524b
diff --git a/plat/amlogic/common/include/aml_private.h b/plat/amlogic/common/include/aml_private.h
index 4923745..724f382 100644
--- a/plat/amlogic/common/include/aml_private.h
+++ b/plat/amlogic/common/include/aml_private.h
@@ -31,6 +31,7 @@
 void aml_scpi_unknown_thermal(uint32_t arg0, uint32_t arg1,
 			      uint32_t arg2, uint32_t arg3);
 void aml_scpi_upload_scp_fw(uintptr_t addr, size_t size, int send);
+uint32_t aml_scpi_get_chip_id(uint8_t *obuff, uint32_t osize);
 
 /* Peripherals */
 void aml_thermal_unknown(void);