Bluetooth: L2CAP: Fix a condition in l2cap_sock_recvmsg()

Smatch complains about the indenting:

    net/bluetooth/l2cap_sock.c:1027 l2cap_sock_recvmsg()
    warn: inconsistent indenting

It looks like this is supposed to be an "else if" condition.

Fixes: 15f02b91 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>