radeapclient - fix send_packet

I spotted two errors in radeapclient.c, introduced in the following
previous commits.
With this fix, radeapclient is now useable again.

1)
Commit: c8a062a112f17a5810d311dc0e0acfe963b2d440
(2014/06/13)

- send_packet(rep, &req);
-
- if (!req) return -1;
+ send_packet(req, &rep);
+ if (!rep) {

Arguments got reversed. Hence segmentation fault later when doing:

for (vp = req->vps; vp != NULL; vp = vpnext) {

Bit of caution on the wording used in radeapclient:
"req" is the request coming FROM the server. (because this is not a
"request" in RADIUS sense, but an EAP-Request within the EAP-SIM
transaction.)
"rep" is the response from the client TO the server (EAP-Response).

2)
Commit: bc3676835c3dcc220ab518d4c3c35962bc0f8be2
(2014/05/02)

In "send_packet":

+ if (!req || !rep || !*rep) return -1;

*rep == NULL is the expected behaviour...