Staging: fwserial: Add blank line after declarations

Add blank line after the structure declaration,
struct fwtty_port *port = tty->driver_data;
Issue found using checkpatch.pl

Signed-off-by: Bhanusree Pola <bhanusreemahesh@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>