Store correct IMSI when retreived from SIMRecords and use it for RuimRecords

Stock stores the IMSI gathered with SIMRecords and uses that value when
RuimRecords wants to get the APN/operator number.

Set System prop "ro.telephony.get_imsi_from_sim=true" to enable this function

Change-Id: I9597002c7472c1ed93826f3d582c3155956c472c