Check eap_get_name() return against NULL to silence static analyzer

Check eap_get_name() return against NULL to silence static analyzer

This cannot really be NULL in practice since cred->eap_method would
point to a valid EAP method. Anyway, to avoid false positive from
analyzers, check the pointer explicitly before printing it.

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