[UPSTREAM] Move backlight handling out of pcf50633 driver

[Andy Green]

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Somebody in the thread at some point said:

Nice work Balaji.

| Can you make the max brightness a #define where it can be an arbitrary
| value such as 100 or 255? I'm also curious about suspend/resume ordering

This will be more important than it sounds.  How about we ourselves
change to 255 as the logical max brightness.  Existing code can find our
actual max brightness down /sys and scale accordingly.

| and turning on the lcd backlight. You need to make sure the lcds are on
| before the backlight to prevent white screen flashes and should turn off
| backlight before the lcds.

Ah Balaji has taken care about it I see, he has added a probe completion
callback into mach_gta02.c that creates the backlight device and forces
its parent to the jbt6k74.  So if I have it right the full device
subtree there is like this

i2c bus ->
~  pcf50633 ->
~    Glamo ->
~      Glamo fb ->
~        Glamo SPI bb bus ->
~          jbt6k74 ->
~             backlight

That looks great for not only killing races but also avoiding white flash.

- -Andy
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