Use dissect_e212_imsi() to dissect IMSI
Fix dissection when MCC starts in the high nibble.
Replace deprecated APIs

Change-Id: Ic08a1db9ee7ebb535bf7914191807304e9f88981
Reviewed-on: https://code.wireshark.org/review/3736
Reviewed-by: Anders Broman <a.broman58@gmail.com>