exynos4x12: liblights: Fix tablets with button backlight

Also, respect the lights API and return errors when attempting to
configure an absent light ID.

Change-Id: Ida430fba2fbfaf646f7e02ce2bd7d9134ae8d917
hwc: Update to API 1.1

Change-Id: I59a1102bb4d8e9622362c8909b122a3b99c656fd
Revert "hwc: Update to API 1.1"

This reverts commit 99f63f2a4fb8037505b34e7665e9b1d717f28d6c.
Derp, this isn't ready to go in.