arm: tegra: hawkeye: apply backlight transfer function

arm: tegra: hawkeye: apply backlight transfer function

Adjust backlight update requests to create a nonlinear
change in brightness (smaller increments at lower
backlight levels, larger increments at higher backlight
levels).
The current curve data is borrowed from Shield Tablet 8.

Bug 1647733

Change-Id: Iccea5b5e34a5cd2ee759fecf7b86a4a0d0b57deb
Signed-off-by: Daniel Solomon <daniels@nvidia.com>
Reviewed-on: http://git-master/r/745148
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>