pibridge-serdev: change semantic of pibridge_req_io()

In function pibridge_req_io() do not return 0 in case of success but
instead return the number of received bytes.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Author: linosanfilippo-kunbus

drivers/tty/serdev/pibridge.c

@@ -500,14 +500,7 @@ int pibridge_req_io(u8 addr, u8 cmd, void *snd_buf, u8 snd_len, void *rcv_buf,
 		return -EBADMSG;
 	}
 
-	if (pkthdr.len < rcv_len) {
-		dev_warn_ratelimited(&pibridge_s->serdev->dev,
-			"received packet smaller than expected (size: %u, expected: %u)\n",
-			pkthdr.len, rcv_len);
-		return -EBADMSG;
-	}
-
-	return 0;
+	return to_receive;
 }
 EXPORT_SYMBOL(pibridge_req_io);