If the EF.EHPLMN exists, it contains the "Equivalent Home PLMN List".
The odd part of that list is that it is not just a list of additional
PLMN identities, but if the first digits of the IMSI are *not* listed
in EF.EHPLMN, then the MCC/MNC of the IMSI prefix is suddently no
longer considered the home network, but the subscriber is roaming.
See TS 23.122: "If the HPLMN code derived from the IMSI is not present
in the EHPLMN list, then it shall be treated as a Visited PLMN for PLMN
selection purposes."
Change-Id: I22d96ab4a424ec5bc1fb02f5e80165c646a748d3
ca6739458e