V4L/DVB (13622): gspca - ov534: Fix a compilation warning.

This warning prevented the sharpness setting to work with the ov965x sensor.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/ov534.c

@@ -1533,7 +1533,7 @@ static void setexposure_96(struct gspca_dev *gspca_dev)
 static void setsharpness_96(struct gspca_dev *gspca_dev)
 {
 	struct sd *sd = (struct sd *) gspca_dev;
-	u8 val;
+	s8 val;
 
 	val = sd->sharpness;
 	if (val < 0) {				/* auto */