mei: fix return value on disconnect timeout

wait_event_timeout can return 0 or the remaining jiffies
so return -ETIME if disconnected state not reached.

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>