Separate OpenSSL engine configuration for Phase 2

Separate OpenSSL engine configuration for Phase 2

I fixed the engine issue in phase2 of EAP-TTLS. The problem was that you
only defined one engine variable, which was read already in phase1. I
defined some new variables:

engine2
engine2_id
pin2

and added support to read those in phase2 wheres all the engine
variables without number are only read in phase1. That solved it and I
am now able to use an engine also in EAP-TTLS phase2.