CI: Migrate support to MbedTLS v2.24.0

This patch migrates the mbedcrypto dependency for TF-A
to mbedTLS repo v2.24.0 which is the latest release tag.
The relevant files are updated to reflect the use of new
version.

Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Change-Id: Id7df567b586c31d74978b3ec8899e15905987e24
diff --git a/arm-env.sh b/arm-env.sh
index 1152578..635c52e 100644
--- a/arm-env.sh
+++ b/arm-env.sh
@@ -25,7 +25,7 @@
 tf_for_scp_tools_src_repo_url="https://gerrit.oss.arm.com/scp/test-framework"
 
 # If not set, the OpenCI would download the tarball from Github every time.
-mbedtls_archive="${mbedtls_archive:-$tfa_downloads/mbedtls/mbedtls-2.18.0.tar.gz}"
+mbedtls_archive="${mbedtls_archive:-$tfa_downloads/mbedtls/mbedtls-2.24.0.tar.gz}"
 
 # Arm Coverity server.
 export coverity_host="${coverity_host:-coverity.cambridge.arm.com}"