CI: Use SCP/MCP v2.7.0 release binaries for CSS platforms

This patch makes use of SCP/MCP v2.7.0 release binaries
for the following FVP CSS platforms:
- rddaniel
- rdn1edge
- rdn1edgex2
- sgi575
- sgm775
- tc0
For sgi575 and sgm775 prebuilt binaries are also updated
from https://releases.linaro.org/members/arm/platforms/20.01

Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Change-Id: Iff561e3aad9f28670066ef53b878128a96f6a697
diff --git a/tc0_utils.sh b/tc0_utils.sh
index 895ec87..993d7e5 100644
--- a/tc0_utils.sh
+++ b/tc0_utils.sh
@@ -9,6 +9,9 @@
 
 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}"
+
 fvp_kernels[fvp-tc-kernel]="$tc_prebuilts/Image"
 fvp_initrd_urls[fvp-tc-ramdisk]="$tc_prebuilts/uInitrd-busybox.0x88000000"