Revert "Add option for switching between UMS and MTP/PTP mode. (1/2)"

This reverts commit 2c76ce08cbdf37dac7cb0cce09b8373a7c3d5d1b.
Revert "LegacyUSB: Squashed commit with updates for 4.2 - CM"

This reverts commit 3ad65c55aa870694195243bd2af1046e714c077c.