[media] ati_remote: Check the checksum

An input report is 4 bytes long, but there are only 12 bits
of actual payload.  The 4 bytes are:
data[0] = 0x14
data[1] = data[2] + data[3] + 0xd5 (a checksum byte)
data[2] = the raw scancode (plus toggle bit in msbit)
data[3] = channel << 4 (the low 4 bits must be zero)

Ignore reports with a bad checksum.
Signed-off-by: George Spelvin <linux@horizon.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/rc/ati_remote.c

@@ -507,8 +507,9 @@ static void ati_remote_input_report(struct urb *urb)
 	 */
 
 	/* Deal with strange looking inputs */
-	if ( (urb->actual_length != 4) || (data[0] != 0x14) ||
-		((data[3] & 0x0f) != 0x00) ) {
+	if ( urb->actual_length != 4 || data[0] != 0x14 ||
+	     data[1] != (unsigned char)(data[2] + data[3] + 0xD5) ||
+	     (data[3] & 0x0f) != 0x00) {
 		ati_remote_dump(&urb->dev->dev, data, urb->actual_length);
 		return;
 	}
@@ -524,9 +525,9 @@ static void ati_remote_input_report(struct urb *urb)
 	remote_num = (data[3] >> 4) & 0x0f;
 	if (channel_mask & (1 << (remote_num + 1))) {
 		dbginfo(&ati_remote->interface->dev,
-			"Masked input from channel 0x%02x: data %02x,%02x, "
+			"Masked input from channel 0x%02x: data %02x, "
 			"mask= 0x%02lx\n",
-			remote_num, data[1], data[2], channel_mask);
+			remote_num, data[2], channel_mask);
 		return;
 	}