Adds support for the Huawei E3276 by sending the shortened form of the
AT^NDISDUP command where possible, as the E3276 fails with an '+CME ERROR:
Incorrect parameters' if encoded_auth is set to 0. This behaviour is slightly
different to the E1820 and K4605 (E372) which will happily establish a
connection with encoded_auth set to 0, 1 or 2.
e684851698