USB: serial: io_ti: add read-port-command helper

Add a read-port-command helper analogous to the send-port-command
helper to take care of the UART module id instead of open coding.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
1 file changed