ci: Use SCP/MCP v2.8.0-dev release binaries for CSS platforms

This patch makes use of SCP/MCP v2.8.0-dev release binaries
for the following FVP CSS platforms:
- rdn1edge
- rdn1edgex2
- sgi575
- sgm775
- tc0

Once the SCP-firmware has released v2.8 version, the binaries
and path will be updated accordingly.

Change-Id: I442523e1bb5d7650d5886d1f588dfb9ba22766f6
Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
diff --git a/rdn1edge_utils.sh b/rdn1edge_utils.sh
index e8908bc..1a34382 100644
--- a/rdn1edge_utils.sh
+++ b/rdn1edge_utils.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 #
-# Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+# Copyright (c) 2019-2021 Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -9,8 +9,8 @@
 
 sgi_prebuilts="${sgi_prebuilts:-$css_downloads/sgi/rdn1edge}"
 
-# Pre-built SCP/MCP v2.7.0 release binaries
-scp_mcp_prebuilts="${scp_mcp_prebuilts:-$css_downloads_270/sgi/rdn1edge}"
+# Pre-built SCP/MCP v2.8.0-dev release binaries
+scp_mcp_prebuilts="${scp_mcp_prebuilts:-$css_downloads_280/sgi/rdn1edge}"
 
 fvp_kernels[fvp-sgi-busybox]="$sgi_prebuilts/Image"
 fvp_initrd_urls[fvp-sgi-ramdisk]="$sgi_prebuilts/ramdisk-busybox.img"