feat(scp): scp/mcp v2.9.0 update - sgi575

Updates sgi575 test suite to use v2.9.0 scp/mcp prebuilds

Signed-off-by: Maksims Svecovs <maksims.svecovs@arm.com>
Change-Id: Idd5ba30290d430fc218a6a647a255c4afd478b08
diff --git a/sgi575_utils.sh b/sgi575_utils.sh
index 852a6d5..0e20b8d 100644
--- a/sgi575_utils.sh
+++ b/sgi575_utils.sh
@@ -9,8 +9,8 @@
 
 sgi_prebuilts="${sgi_prebuilts:-$css_downloads/sgi/sgi575}"
 
-# Pre-built SCP/MCP v2.8.0 release binaries
-scp_mcp_prebuilts="${scp_mcp_prebuilts:-$css_downloads_280/sgi/sgi575}"
+# Pre-built SCP/MCP binaries
+scp_mcp_prebuilts="${scp_mcp_prebuilts:-$scp_mcp_downloads/sgi575/release}"
 
 fvp_kernels[fvp-sgi-busybox]="$sgi_prebuilts/Image"
 fvp_initrd_urls[fvp-sgi-ramdisk]="$sgi_prebuilts/ramdisk-busybox.img"