staging: dgrp: fix some warnings

Just squashing these to get them out of the analysis queue.

nd_ps_desc is an array not a pointer so comparing it with NULL is silly (be
nice if gcc shouted about this). And there are some slightly pointless
comparisons too.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>