connection: return false on read error

Return false to indicate that there is no more data to read or else
we add the -1 to buffer_size and things go wrong..

src/modules/module-protocol-native/connection.c

@@ -150,6 +150,7 @@ static bool refill_buffer(struct pw_protocol_native_connection *conn, struct buf
 				continue;
 			if (errno != EAGAIN || errno != EWOULDBLOCK)
 				goto recv_error;
+			return false;
 		}
 		break;
 	}