Add key layout and device file for Reference RCU

Adding key layout and device configuration file
for Google Reference RCU.
The VID/PID pair used in file name is speicifically for
Reference RCU, which supports both G10 and G20.

b/173100313
test: manually on custom build for ADT-3

Change-Id: I2048012fb91adfc6a2f61065ba262d5ed344c673