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/tc0_utils.sh b/tc0_utils.sh
index 993d7e5..b81d148 100644
--- a/tc0_utils.sh
+++ b/tc0_utils.sh
@@ -10,7 +10,7 @@
 tc_prebuilts="${tc_prebuilts:-$tfa_downloads/total_compute/tc0}"
 
 # Pre-built SCP v2.7.0 release binaries
-scp_prebuilts="${scp_prebuilts:-$tfa_downloads/total_compute_scp_2.7.0/tc0}"
+scp_prebuilts="${scp_prebuilts:-$tfa_downloads/total_compute_scp_2.8.0-dev/tc0}"
 
 fvp_kernels[fvp-tc-kernel]="$tc_prebuilts/Image"
 fvp_initrd_urls[fvp-tc-ramdisk]="$tc_prebuilts/uInitrd-busybox.0x88000000"