Added 'sofia3gr.ThermalManagement' interface to sofia3gr plugin and
floated 'TransmitPowerThrottling' as an ofono property under that,
to support modem throttling.
'sofia3gr.ThermalManagement'
1.Will be available ONLY if modem throttling is supported in RIL.
This is determined by sending a RIL request during ofono start,
to get current throttling state. If it succeeds, interface is
published otherwise not.
'TransmitPowerThrottling'
1.GetProperties will be allowed both when modem is ON & OFF.
2.GetProperties will be serviced by looking it up from state
information maintained inside ofono. No RIL call will be made.
3.SetProperty will be allowed ONLY when modem is ON.
4.SetProperty request will be forwarded to RIL ONLY if
new state != current state. If RIL request succeeds, state
information will be updated and also, a property change signal
will be emitted.