EAP-pwd: Fix processing of group setup failure

EAP-pwd: Fix processing of group setup failure

If invalid group was negotiated, compute_password_element() left some of
the data->grp pointer uninitialized and this could result in
segmentation fault when deinitializing the EAP method. Fix this by
explicitly clearing all the pointer with eap_zalloc(). In addition,
speed up EAP failure reporting in this type of error case by indicating
that the EAP method execution cannot continue anymore on the peer side
instead of waiting for a timeout.

Signed-off-by: Jouni Malinen <j@w1.fi>