tools: iio: Remove explicit NULL comparison

Remove explicit NULL comparison and write it in its simpler form as
recommended by checkpatch.pl.

Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
3 files changed