adb: Conditionally restore support for legacy f_adb interface

 * Restore full support of USB and ADB on devices using the
    legacy f_adb kernel drivers (to enable it, devices must
    set TARGET_USES_LEGACY_ADB_INTERFACE flag to true)

 * Forward port with commits:
    'adb: kill adb_thread_{create, join, detach, exit}'

This reverts commit 183b73e6.
Change-Id: I37f3ad237ee38a23736b2378e790a97efdf95bf0
Signed-off-by: Adrian DC <radian.dc@gmail.com>