msm: mdss: Finalize gamma interface and cleanup

- Remove all sysfs files of unused commands
- Remove auto sync for negative polarities, these must be written separately
- Protect offset bit of white point command as well
- Apply white point bit 2 as duplicate of bit 1
msm: mdss: Send panel commands via separate function

Sending panel comnmands is very expensive, add a separate function to
accomplish this. Once all commands have been stored write anything to
the kgamma_send file.