CSS: Changes for SDS framework

This patch does the required changes to enable CSS platforms
to build and use the SDS framework. Since SDS is always coupled with
SCMI protocol, the preexisting SCMI build flag is now renamed to
`CSS_USE_SCMI_SDS_DRIVER` which will enable both SCMI and SDS on
CSS platforms. Also some of the workarounds applied for SCMI are
now removed with SDS in place.

Change-Id: I94e8b93f05e3fe95e475c5501c25bec052588a9c
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
diff --git a/plat/arm/css/common/css_bl2_setup.c b/plat/arm/css/common/css_bl2_setup.c
index c98b2ff..9b4800e 100644
--- a/plat/arm/css/common/css_bl2_setup.c
+++ b/plat/arm/css/common/css_bl2_setup.c
@@ -48,10 +48,14 @@
 	return ret;
 }
 
-#ifdef EL3_PAYLOAD_BASE
+#if !CSS_USE_SCMI_SDS_DRIVER
+# ifdef EL3_PAYLOAD_BASE
+
 /*
  * We need to override some of the platform functions when booting an EL3
- * payload.
+ * payload. These needs to be done only for SCPI/BOM SCP systems as
+ * in case of SDS, the structures remain in memory and doesn't need to be
+ * overwritten.
  */
 
 static unsigned int scp_boot_config;
@@ -82,4 +86,7 @@
 	zeromem((void *) ARM_SHARED_RAM_BASE, 128);
 	mmio_write_32(SCP_BOOT_CFG_ADDR, scp_boot_config);
 }
-#endif /* EL3_PAYLOAD_BASE */
+
+# endif /* EL3_PAYLOAD_BASE */
+
+#endif /* CSS_USE_SCMI_SDS_DRIVER */