eap: fix config realm matching

The source identity for the realm calculation is not set to the current matching one, it results in incorrect realm length and might cause memory access violation.

Bug: 244025119
Test: atest vts
      connect to an EAP network with pseudonym
Change-Id: Ie7031f2f889e3c66b74c6d70aec9ba25a24ba5e2
1 file changed