Revert "UMS [2/6]: Add option for switching between UMS and MTP/PTP mode."

This reverts commit 9343ae01242dc0fa4a003e2eb3574fb3104cff9b.

Conflicts:
	services/java/com/android/server/usb/LegacyUsbDeviceManager.java
Revert "UMS [5/6]: Allow mounting of multiple volumes via mass storage (framework part)"

This reverts commit 263877e6e09191db1fe935b8344e02a993586976.
Revert "UMS [6]: Make "SD Card removed" notification dismissible if the removed SD Card is not the primary storage"

This reverts commit 05e4e9d25104d419df1d05b516a37379c201a08e.