[RTT] RangeResult RSSI now in units of dB

Changed from units of -0.5dB to units of +1dB (original is what comes
from the firmware).

Per API council feedback.

Bug: 73088768
Test: unit tests & integration tests
Change-Id: I77ccbf76f947f29b24a701626e0a1517dd85729e
2 files changed