fix(lts): static checks to point to lts

Changing references in static checks script from origin/master to
origin/lts-v2.8

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: Ib954b64df2520e375a2479d7b04ee0a8083f2867
diff --git a/script/static-checks/check-banned-api.py b/script/static-checks/check-banned-api.py
index 84d5b0e..30585bd 100755
--- a/script/static-checks/check-banned-api.py
+++ b/script/static-checks/check-banned-api.py
@@ -168,7 +168,7 @@
                         help="""
                         Base commit in patch mode (default: %(default)s)
                         """,
-                        default="master")
+                        default="lts-v2.8")
     parser.add_argument("--to-ref",
                         help="""
                         Final commit in patch mode (default: %(default)s)