MIPS: qi_lb60: Migrate to devicetree

Move all the platform data to devicetree.

The only bit dropped is the PWM beeper, which requires the PWM driver
to be updated. I figured it's okay to remove it here since it's really
a non-critical device, and it'll be re-introduced soon enough.

The other change is the CS line of the SPI is now set as active low. The
SPI core would have forced "active low" anyway, unless the 'spi-cs-high'
property is set.

In the process of moving to devicetree, we also switched to new drivers:
- We use the simple-audio-card and simple-amplifier drivers instead of
  the custom ASoC code;
- We use the new Ingenic DRM driver coupled with the GiantPlus GPM940B0
  DRM panel driver instead of the old framebuffer driver;
- We use the new jz4780-dma driver instead of the old jz4740-dma one;
- We use the ingenic-nand and jz4740-ecc drivers instead of the old
  jz4740-nand driver;
- We use ingenic-battery instead of jz4740-battery;
- We use iio-hwmon instead of jz4740-hwmon;
- We use ingenic-iio instead of the old jz4740-adc MFD driver.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
[paul.burton@mips.com:
    Drop the unused & undocumented ili8960 spi@0 node.]
Signed-off-by: Paul Burton <paul.burton@mips.com>