Consider both ATR and num of ports reported to decide MEP support.

1. Even ATR is suggesting eUICC supports MEP, framework or modem can still
disable MEP based on carrier restrictions. If MEP is disabled at lower
layer, it will report only one port to AP.
2. Given ATR parsing is done by AnswerToReset class which has the logging
and memeber variables, no need to keep a copy on UiccSlot just for
mATR.MEP

Bug: 213503081
Test: Manual
Change-Id: I63d74927ba5698d8fc26605e85d8cac606dddfb5