overlay: mms: add overlay for US Cellular

* This carrier needs SplitMMS enabled like sprint

Change-Id: I7e1604d63b86160dd4283066c6fa8af28bfa46d1
mms overlay: remove un-needed configs in klteusc mms_Config.xml

Change-Id: I5b6f8d7215527d53c5f9c0b9d4ac292e4b1781a2