Revert "UsbSettings: Add UMS mode support"

This reverts commit bd5d23d8af6e7d1521374cfc0302f5dbaac2ab43.
ums: support UMS on any volume

Change-Id: I43668a5200d30cef953e0d3e9ded2d8cf0cbbd22
Vectone UK (MNC01) considered non-roaming on T-Mobile (MNC30)

Change-Id: Id74c854f958be721be12451a124cfd2f8b150255