Staging: comedi: drivers: comedi_test: Avoid multiple line dereference

Fix checkpatch warning "Avoid multiple line dereference"
using a pointer variable to avoid line wrap.

Signed-off-by: Cheah Kok Cheong <thrust73@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/comedi_test.c

@@ -480,11 +480,11 @@ static void waveform_ao_timer(unsigned long arg)
 			/* output the last scan */
 			for (i = 0; i < cmd->scan_end_arg; i++) {
 				unsigned int chan = CR_CHAN(cmd->chanlist[i]);
+				unsigned short *pd;
 
-				if (comedi_buf_read_samples(s,
-							    &devpriv->
-							     ao_loopbacks[chan],
-							    1) == 0) {
+				pd = &devpriv->ao_loopbacks[chan];
+
+				if (!comedi_buf_read_samples(s, pd, 1)) {
 					/* unexpected underrun! (cancelled?) */
 					async->events |= COMEDI_CB_OVERFLOW;
 					goto underrun;