staging: fwserial: (coding style) removing "!= NULL" to comply with checkpatch.pl

Removing two "!= NULL" from fwserial.c as suggested by checkpatch.pl.
Note that the associated expression "port->port.console" is a 1-bit-field
that is already assumed as an implicit boolean (that is: without comparison)

Signed-off-by: Dominique van den Broeck <domdevlin@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>