backlight: lms283gf05: Convert to GPIO descriptors

This converts the lms283gf05 backlight driver to use GPIO
descriptors and switches the single PXA Palm Z2 device
over to defining these.

Since the platform data was only used to convey GPIO
information we can delete the platform data header.

Notice that we define the proper active low semantics in
the board file GPIO descriptor table (active low) and
assert the reset line by bringing it to "1" (asserted).

Cc: Marek Vasut <marex@denx.de>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Mack <daniel@zonque.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>