build: dont break roomservice if root device dir is missing

just create it then

Change-Id: I5f71381885abf29a36ee6deb019a5ce1e6eee052
diff --git a/build/tools/roomservice.py b/build/tools/roomservice.py
index 8800407..8e18545 100755
--- a/build/tools/roomservice.py
+++ b/build/tools/roomservice.py
@@ -191,6 +191,8 @@
 
 def parse_device_from_folder(device):
     search = []
+    if not os.path.isdir("device"):
+        os.mkdir("device")
     for sub_folder in os.listdir("device"):
         if os.path.isdir("device/%s/%s" % (sub_folder, device)):
             search.append("device/%s/%s" % (sub_folder, device))