fbdev: viafb: use new array-copying-wrapper

viafbdev.c utilizes memdup_user() to copy an array from userspace.

There is a new wrapper, specifically designed for copying arrays. Use
this one instead.
Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>

drivers/video/fbdev/via/viafbdev.c

@@ -574,7 +574,7 @@ static int viafb_ioctl(struct fb_info *info, u_int cmd, u_long arg)
 		break;
 
 	case VIAFB_SET_GAMMA_LUT:
-		viafb_gamma_table = memdup_user(argp, 256 * sizeof(u32));
+		viafb_gamma_table = memdup_array_user(argp, 256, sizeof(u32));
 		if (IS_ERR(viafb_gamma_table))
 			return PTR_ERR(viafb_gamma_table);
 		viafb_set_gamma_table(viafb_bpp, viafb_gamma_table);