backlight: fix broken regulator API usage in l4f00242t03

The regulator support in the l4f00242t03 is very non-idiomatic.  Rather
than requesting the regulators based on the device name and the supply
names used by the device the driver requires boards to pass system
specific supply names around through platform data.  The driver also
conditionally requests the regulators based on this platform data, adding
unneeded conditional code to the driver.

Fix this by removing the platform data and converting to the standard
idiom, also updating all in tree users of the driver.  As no datasheet
appears to be available for the LCD I'm guessing the names for the
supplies based on the existing users and I've no ability to do anything
more than compile test.

The use of regulator_set_voltage() in the driver is also problematic,
since fixed voltages are required the expectation would be that the
voltages would be fixed in the constraints set by the machines rather than
manually configured by the driver, but is less problematic.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>