tf-coverity: add MHUv3 build coverage

Add a TC build that uses MHUv3 instead of MHUv2 when communicating with
RSE. This enables coverage of mhu_v3_x.c and mhu_wrapper_v3_x.c before
main platforms that uses MHUv3 are available.

Change-Id: I141376d76eda0788a999f029136a45287d2003d2
Signed-off-by: Joel Goddard <joel.goddard@arm.com>
diff --git a/script/tf-coverity/tf-cov-make b/script/tf-coverity/tf-cov-make
index 6dfba12..bbfbed2 100755
--- a/script/tf-coverity/tf-cov-make
+++ b/script/tf-coverity/tf-cov-make
@@ -318,7 +318,8 @@
 # Total Compute platforms
 #
 clean_build $(common_flags) PLAT=tc TARGET_PLATFORM=1 ${ARM_TBB_OPTIONS}
-clean_build $(common_flags) PLAT=tc TARGET_PLATFORM=2 ${ARM_TBB_OPTIONS} MEASURED_BOOT=1
+clean_build $(common_flags) PLAT=tc TARGET_PLATFORM=2 ${ARM_TBB_OPTIONS} MEASURED_BOOT=1 \
+    PLAT_MHU_VERSION=3
 clean_build $(common_flags) PLAT=tc TARGET_PLATFORM=2 ${ARM_TBB_OPTIONS} MEASURED_BOOT=1 \
     DICE_PROTECTION_ENVIRONMENT=1 QCBOR_DIR=$(pwd)/qcbor
 clean_build $(common_flags) PLAT=tc TARGET_PLATFORM=2 ${ARM_TBB_OPTIONS} PLATFORM_TEST=rss-rotpk