staging: comedi: adl_pci9118: if test should use logical AND not bitwise AND

This quiets a couple sparse warnings about:

warning: dubious: !x & y

Also, remove the unnecessary parentheses around the variables.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/adl_pci9118.c

@@ -1735,7 +1735,7 @@ static int check_channel_list(struct comedi_device *dev,
 							"can't be mixtured!");
 				return 0;
 			}
-			if ((!devpriv->usemux) & (differencial) &
+			if (!devpriv->usemux && differencial &&
 			    (CR_CHAN(chanlist[i]) >= this_board->n_aichand)) {
 				comedi_error(dev,
 					     "If AREF_DIFF is used then is "