pps: Additional cleanups in uart_handle_dcd_change

An extension of the previous commit, there is no semantic change
here, just fewer lines of source code.

Signed-off-by: George Spelvin <linux@horizon.com>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>