This reverts commit bdf3d3597b, which
broke pySim.utils.dec_mnc_from_plmn(). According to 3GPP TS 31.102,
which points to TS 24.008, the three-digit EHPLMN shall be encoded
as shown below (ASCII-art interpretation):
0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| MCC Digit 2 | MCC Digit 1 |
+---+---+---+---+---+---+---+---+
| MNC Digit 3 | MCC Digit 3 |
+---+---+---+---+---+---+---+---+
| MNC Digit 2 | MNC Digit 1 |
+---+---+---+---+---+---+---+---+
So the original implementation was correct, and we even had a unit
test for it. Most likely, the SIM card itself was programmed
incorrectly?
Makes 'testDecMNCfromPLMN_threeDigitMNC' pass again.
Change-Id: If6bf5383988ad442e275efc7c5a159327d104879
b271be3dc0