backlight: drop max_brightness to 254

Change-Id: I1a853934b421d308f8a6c1c5aed7d3a1b9924cc1
add variant defconfigs

Change-Id: Ib3b7169e0899838e4d39020d03287e7fd824aa4e
defconfig updates

Change-Id: I83ff8cf6530f8a5403539a0ae015aed4eb12a099