mISDN: Fix handling of receive buffer size in L1oIP

The size of receive buffer pointer was used to get size of
receive buffer instead of recvbuf_size itself, so only 4/8
bytes could be transfered.

This is a regression to 2.6.30 introduced by commit
8c90e11e3543d7de612194a042a148caeaab5f1d ("mISDN: Use
kernel_{send,recv}msg instead of open coding")

Signed-off-by: Andreas Eversberg <andreas@eversberg.eu>
Signed-off-by: Karsten Keil <keil@b1-systems.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/isdn/mISDN/l1oip_core.c

@@ -731,10 +731,10 @@ l1oip_socket_thread(void *data)
 	while (!signal_pending(current)) {
 		struct kvec iov = {
 			.iov_base = recvbuf,
-			.iov_len = sizeof(recvbuf),
+			.iov_len = recvbuf_size,
 		};
 		recvlen = kernel_recvmsg(socket, &msg, &iov, 1,
-					 sizeof(recvbuf), 0);
+					 recvbuf_size, 0);
 		if (recvlen > 0) {
 			l1oip_socket_parse(hc, &sin_rx, recvbuf, recvlen);
 		} else {