Revert "Improve ambient backlight sensor control."

This reverts commit fa7f88db81b2521538d24ef9d19f8dbb409c75d9.

Change-Id: I34d57929148e7aaf82fd20ff03c58e8b092ebc4e
Revert "Complete overhaul of the button led logic."

This reverts commit e8516e32de9fea3401aa1c75e84a2ae250e31a88.

Change-Id: Ib6bf19b790590d6a6fc1dccf8d4778cbd85a2e4a