msm: mdss: Display gamma control

TODO: confirm rgb channels, identify other tunables, cleanup,
apply values without switching screen (off and) on.

sysfs: /sys/devices/qcom,mdss_dsi_jdi_command_ors.69/*
msm: mdss: Apply commands values without switching screen (off and) on
msm: mdss: Remove tunable for command 32

Even slight changes look ugly or distort the screen.
msm: mdss: distinguish between Gamma RGB polarity Positive/Negative

Signed-off-by: Paul Reioux <reioux@gmail.com>
msm: mdss: Remove sysfs for unused commands
msm: mdss: Identify white point in sysfs
msm: mdss: Add safety check for user input

Leave more checks either to the control app or the user's intelligence.
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.
msm: mdss: Add hardware revision check

Our gamma interface works with both current hardware revisions,
11 and 11j, although all testing was carried out on 11. As we
don't know about possible future revisions, let's bail out until
correct offsets for panel commands have been added.

Signed-off-by: Paul Reioux <reioux@gmail.com>
msm: mdss: Use workqueue to send panel commands

Sending panel commands is known to be expensive, honor this by
scheduling this task. Also check for panel state and send commands
only when we're actually awake.

These fixes adress bug reports regarding behaviour during boot.
msm: mdss: Find a stable sysfs node for the gamma interface

Move sysfs files to /sys/module/dsi_panel/*
msm: mdss: Reset panel to apply RGB gamma data

Writing to the reset gpios produces a short flicker. This however
appears to be the only reliable method to apply RGB gamma data
without switching the panel off and on again.