The screen brightness float setting initially did not exist when upgrading the device software. This change ensures the float and int values are synchronised on the system start-up. Bug: 167651957 Test: manual - set autobrightness off, upgrade from Q to R, and check brightness value in settings. Change-Id: I2a3b996c8747e3c5f1d181bbdd438c70bf23d08b (cherry picked from commit 96f43f21b3a3021762c2d213d8958590127cae36)