ti-st: use worker instead of calling st_int_write in wake up

The wake up method is called with the port lock held. The st_int_write
method calls port->ops->write with tries to acquire the lock again,
causing CPU to wait infinitely. Right way to do is to write data to port
in worker thread.

Signed-off-by: Muhammad Hamza Farooq <mfarooq@visteon.com>
Signed-off-by: Jacob Siverskog <jacob@teenage.engineering>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>