Testra RSSI compliance

Devices that support 4 bar signal strength
indication should display the bars as follow:

4 bar   RSRP   > -90
3 bar   -90 ≥    RSRP   > -100
2 bar  -100 ≥   RSRP   > -115
1 bar   -115 ≥  RSRP   > -120
0 bar   RSRP    ≤ -120
      or No Sync to LTE Reference Signals

Bug=37187586

Change-Id: I2a76aabdf6d8ef1be3a05a90643b1e670f929bc3