adb: kick the transport after sending the "adb root" command

This is needed because the USB driver on the device no longer resets the bus
when exits and restarts.
Since the host side adb no longer detects that adbd has restarted we need
to reset the connection on the host side now.

Change-Id: I1a8eabd292e8b45c34fa07a8a8b8c609cc15648d
Signed-off-by: Mike Lockwood <lockwood@android.com>