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/sgm775_utils.sh b/sgm775_utils.sh
index 0028bce..a15a892 100644
--- a/sgm775_utils.sh
+++ b/sgm775_utils.sh
@@ -1,16 +1,16 @@
 #!/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
 #
 
 source "$ci_root/fvp_utils.sh"
 
-# Pre-built SCP v2.7.0 release binaries
+# Pre-built SCP v2.8.0-dev release binaries
 # Files from
 # https://releases.linaro.org/members/arm/platforms/20.01/sgm775-ack-busybox-uboot.zip
-sgm_prebuilts="${sgm_prebuilts:-$css_downloads_270/sgm/sgm775}"
+sgm_prebuilts="${sgm_prebuilts:-$css_downloads_280/sgm/sgm775}"
 
 fvp_kernels[fvp-sgm-kernel]="$sgm_prebuilts/uImage.0x80080000.mobile_bb"
 fvp_initrd_urls[fvp-sgm-ramdisk]="$sgm_prebuilts/uInitrd-busybox.0x88000000"