PT:VZW:CV MMS not able to be sent with messenger app

Bug 17506557

I missed a spot where the mcc/mnc was getting set without updating the
siminfo record. This affected Sprint phones and perhaps others. As a result,
the mcc/mnc for the one and only subscription record had an mcc/mnc of zero
and the default mms_config for that mcc/mnc couldn't be loaded.

Change-Id: Iea0222a29a1f9426a4cdf4b9946620e2d02615e7