feat(xilinx): add support to get chipid

Add support for PM API SYS to get the chip ID from the target.
The API calls the IPI command to read the Chip idcode and revision.

Change-Id: Id4d7d812cbf77c5e2fc7785b8afb379214f8dd19
Signed-off-by: Akshay Belsare <akshay.belsare@amd.com>
diff --git a/plat/xilinx/common/pm_service/pm_api_sys.c b/plat/xilinx/common/pm_service/pm_api_sys.c
index c36a0ec..2f47cca 100644
--- a/plat/xilinx/common/pm_service/pm_api_sys.c
+++ b/plat/xilinx/common/pm_service/pm_api_sys.c
@@ -648,3 +648,19 @@
 
 	return pm_ipi_send_sync(primary_proc, payload, NULL, 0);
 }
+
+/**
+ * pm_get_chipid() - Read silicon ID registers
+ * @value:	Buffer for two 32bit words.
+ *
+ * @return:	Returns status, either success or error+reason and,
+ *		optionally, @value.
+ */
+enum pm_ret_status pm_get_chipid(uint32_t *value)
+{
+	uint32_t payload[PAYLOAD_ARG_CNT];
+
+	PM_PACK_PAYLOAD1(payload, LIBPM_MODULE_ID, SECURE_FLAG, PM_GET_CHIPID);
+
+	return pm_ipi_send_sync(primary_proc, payload, value, 2);
+}