static-checks: use origin/master instead of master as base branch

In some CI testing scenarios, there are no local branches, just remotes, so
as a safer approach, use 'origin/master' instead of 'master'. Base
branch is used to find common parent ancestor between
base (origin/master) and user patchset's (FETCH_HEAD) branches.

Change-Id: I36940ac043f45bda6b94e8787b29f319a5f4acba
Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
diff --git a/script/static-checks/static-checks-coding-style-line-endings.sh b/script/static-checks/static-checks-coding-style-line-endings.sh
index 5442f7d..bd31e2d 100755
--- a/script/static-checks/static-checks-coding-style-line-endings.sh
+++ b/script/static-checks/static-checks-coding-style-line-endings.sh
@@ -15,7 +15,7 @@
 
 if [[ "$2" == "patch" ]]; then
     cd "$1"
-    parent=$(git merge-base HEAD master | head -1)
+    parent=$(git merge-base HEAD origin/master | head -1)
     git diff ${parent}..HEAD --no-ext-diff --unified=0 --exit-code -a --no-prefix | grep -E "^\+" | \
     grep --files-with-matches $'\r$' &> "$LOG_FILE"
 else