staging: unisys: cleanup NULL comparisons in virthba.c

Fix all comparisons to NULL so that they don't use NULL anymore.

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/staging/unisys/virthba/virthba.c
Simple merge