gbefb: unsigned var->pixclock cannot be less than 0

unsigned var->pixclock cannot be less than 0
Signed-off-by: NRoel Kluin <roel.kluin@gmail.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/video/gbefb.c

@@ -912,6 +912,7 @@ static int gbefb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
 	unsigned int line_length;
 	struct gbe_timing_info timing;
+	int ret;
 
 	/* Limit bpp to 8, 16, and 32 */
 	if (var->bits_per_pixel <= 8)
@@ -930,8 +931,10 @@ static int gbefb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 
 	var->grayscale = 0;	/* No grayscale for now */
 
-	if ((var->pixclock = compute_gbe_timing(var, &timing)) < 0)
-		return(-EINVAL);
+	ret = compute_gbe_timing(var, &timing);
+	var->pixclock = ret;
+	if (ret < 0)
+		return -EINVAL;
 
 	/* Adjust virtual resolution, if necessary */
 	if (var->xres > var->xres_virtual || (!ywrap && !ypan))