refactor(fvp): move certain tests to 11.24 FVP

There is known bug in FVP-11.25 and 11.26 that doesn't power down
secondary cores correctly when core threads are used.

So to avoid the test failure on 11.26 use 11.24 FVP.

Change-Id: I579aef3e11b177a8d3ef10e793441e6490ad6bd3
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/utils.sh b/utils.sh
index 24c39b3..82cd731 100644
--- a/utils.sh
+++ b/utils.sh
@@ -546,6 +546,9 @@
 jenkins_url="${jenkins_url:-https://ci.trustedfirmware.org/}"
 
 # Model revisions
+model_version_11_24="${model_version:-11.24}"
+model_build_11_24="${model_build:-24}"
+
 model_version="${model_version:-11.26}"
 model_build="${model_build:-11}"
 model_flavour="${model_flavour:-Linux64_GCC-9.3}"