staging: dgnc: remove redundant condition check

dgnc_board(brd) was already checked for NULL before calling
neo_parse_isr(). And also port doesn't need to check.

Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>