[media] vpx3220: signedness bug in vpx3220_fp_read()

The intent was to return -1 on error and that's what the callers expect
but the current code returns USHRT_MAX instead.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/i2c/vpx3220.c

@@ -124,7 +124,7 @@ static int vpx3220_fp_write(struct v4l2_subdev *sd, u8 fpaddr, u16 data)
 	return 0;
 }
 
-static u16 vpx3220_fp_read(struct v4l2_subdev *sd, u16 fpaddr)
+static int vpx3220_fp_read(struct v4l2_subdev *sd, u16 fpaddr)
 {
 	struct i2c_client *client = v4l2_get_subdevdata(sd);
 	s16 data;