V4L/DVB (10670): tw9910: bit mask operation fix on tw9910_mask_set.

Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/tw9910.c

@@ -460,9 +460,11 @@ static int tw9910_mask_set(struct i2c_client *client, u8 command,
 			   u8 mask, u8 set)
 {
 	s32 val = i2c_smbus_read_byte_data(client, command);
+	if (val < 0)
+		return val;
 
 	val &= ~mask;
-	val |=  set;
+	val |= set & mask;
 
 	return i2c_smbus_write_byte_data(client, command, val);
 }