Auto brightness: Increase max of max_lux to 6000

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Add tunables for updated interactive governor

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Add SD read ahead option

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
2.7.5