wwan-mm: Handle access-tec bitmasks better

The switch statement missed things like

  MM_MODEM_ACCESS_TECHNOLOGY_GPRS | MM_MODEM_ACCESS_TECHNOLOGY_GSM

so instead of adding all possible combinations to the switch use if / else instead and check from newest generation to oldest ones.

This makes the mobile network generation show in more cases.

Signed-off-by: Guido Günther agx@sigxcpu.org