GenericDeviceInfo: Guard field access with a version check.

RELEASE_OR_CODENAME only exists on Android R and higher and
the device-info library is used by GTS which produces a multi
release binary that's expected to run on versions as early as
Android 8.

Test: make compatibility-device-info
Test: run GTS on a Q device
Bug: 152442869
Change-Id: I2833a1f2c5a7600df915be517758ed9ccb583971