staging: comedi: Improved readability of function comedi_nsamples_left.

Improve readability of comedi_nsamples_left:
a) Reduce nesting by using more return statements.
b) Declare variables scans_left and samples_left at start of function.
c) Change type of scans_Left to unsigned long long to avoid cast.
Signed-off-by: Chris Opperman <eklikeroomys@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers.c

@@ -473,21 +473,21 @@ unsigned int comedi_nsamples_left(struct comedi_subdevice *s,
 {
 	struct comedi_async *async = s->async;
 	struct comedi_cmd *cmd = &async->cmd;
+	unsigned long long scans_left;
+	unsigned long long samples_left;
 
-	if (cmd->stop_src == TRIG_COUNT) {
-		unsigned int scans_left = __comedi_nscans_left(s, cmd->stop_arg);
-		unsigned int scan_pos =
-		    comedi_bytes_to_samples(s, async->scan_progress);
-		unsigned long long samples_left = 0;
-
-		if (scans_left) {
-			samples_left = ((unsigned long long)scans_left *
-					cmd->scan_end_arg) - scan_pos;
-		}
+	if (cmd->stop_src != TRIG_COUNT)
+		return nsamples;
 
-		if (samples_left < nsamples)
-			nsamples = samples_left;
-	}
+	scans_left = __comedi_nscans_left(s, cmd->stop_arg);
+	if (!scans_left)
+		return 0;
+
+	samples_left = scans_left * cmd->scan_end_arg -
+		comedi_bytes_to_samples(s, async->scan_progress);
+
+	if (samples_left < nsamples)
+		return samples_left;
 	return nsamples;
 }
 EXPORT_SYMBOL_GPL(comedi_nsamples_left);