CSS: Reorganize the SCP Image transfer functionality

The SCP_BL2 is transferred to SCP during BL2 image load and authenticate
sequence. The Boot-Over-MHU (BOM) protocol is used as transport for this. After
the SCP boots using the transferred image, the AP CPU waits till the `READY`
message is received from SCP. This patch separates the API for transport of
image from the wait for `READY` message and also moves the related files to
the `css/drivers` folder. The previous API `scp_bootloader_transfer` is
renamed to `css_scp_boot_image_xfer` to reflect the css naming convention.
This reorganisation also allows easier switch to a different transport
(eg: Shared Data Structure based transfer) in future

Change-Id: I8a96f9c4616ffde6dbfdf7c18f6f6f8bfa40bbf0
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
diff --git a/plat/arm/css/common/css_bl2u_setup.c b/plat/arm/css/common/css_bl2u_setup.c
index cc18758..d225151 100644
--- a/plat/arm/css/common/css_bl2u_setup.c
+++ b/plat/arm/css/common/css_bl2u_setup.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,7 +7,7 @@
 #include <bl_common.h>
 #include <debug.h>
 #include <plat_arm.h>
-#include "css_scp_bootloader.h"
+#include "../drivers/scp/css_scp.h"
 
 /* Weak definition may be overridden in specific CSS based platform */
 #pragma weak bl2u_plat_handle_scp_bl2u
@@ -40,10 +40,13 @@
 
 	INFO("BL2U: Initiating SCP_BL2U transfer to SCP\n");
 
-	ret = scp_bootloader_transfer((void *)scp_bl2u_image_info.image_base,
+	ret = css_scp_boot_image_xfer((void *)scp_bl2u_image_info.image_base,
 		scp_bl2u_image_info.image_size);
 
 	if (ret == 0)
+		ret = css_scp_boot_ready();
+
+	if (ret == 0)
 		INFO("BL2U: SCP_BL2U transferred to SCP\n");
 	else
 		ERROR("BL2U: SCP_BL2U transfer failure\n");