Wifi: Select SIMcard number based on index instead of displayname

The selected SIMcard number is saved to configuration based on display
names, while doing EAP authentication using SIM/AKA/AKAPRIME. This leads
to selecting wrong SIMcard number if the display names of SIM cards are
same.This commit ensures to select SIMcard number based on index instead
of SIM display names.

Change-Id: Ic48af29428b49b9302cd136aae6bf88aa53521bc
CRs-Fixed: 934268