tf-a-builder: Allow to specify qa-tools branch to use

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: If169e6452ef7522872a0198f4f1b71dd8687f380
diff --git a/tf-a-builder/lava-log-process.sh b/tf-a-builder/lava-log-process.sh
index 68a90ef..3b96069 100755
--- a/tf-a-builder/lava-log-process.sh
+++ b/tf-a-builder/lava-log-process.sh
@@ -17,7 +17,7 @@
                 # Generate Code Coverate Report in case there are traces available
                 if find covtrace-*.log; then
                     if [ ! -d "${WORKSPACE}/qa-tools" ]; then
-                        git clone ${QA_TOOLS_REPO} ${WORKSPACE}/qa-tools
+                        git clone ${QA_TOOLS_REPO} -b ${QA_TOOLS_BRANCH:-master} ${WORKSPACE}/qa-tools
                     fi
                     cd ${WORKSPACE}/qa-tools/coverage-tool/coverage-reporting
                     ./branch_coverage.sh \