gemalto: netmon measurements scaling

Gemalto modem reports raw measurements in dBm. Reported values may
include negative numbers. Meanwhile oFono follows ETSI TS 27.007,
so negative numbers do not really exist at the API level.

Modify gemalto netmon driver to report measurements according to
27.007. For this purpose re-scale from what Gemalto firmware
reports into something that 27.007 recommends.
1 file changed