ril.cpp: Correct RSRP and RSRQ values reported by Google Play Ed RIL

The GPE RIL reports RSRP and RSRQ as dBm*10, not dBm, when sending the
data for CellInfoLte. Divide the reported values by 10 to conform with
the API.

This should fix fluctuating signal bars (apparent 0 signal strength
with -70 dBm) on jewel and m7spr.

Change-Id: I69f8917f027bf4cf5604c22e3c199c58f42e21d4