Improve SPI support for Ingenic SoCs.

Improve SPI support for Ingenic SoCs.

Merge series from 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>:

1.Add support for using GPIOs as chip select lines on Ingenic SoCs.
2.Add support for probing the spi-ingenic driver on the JZ4775 SoC,
  the X1000 SoC, and the X2000 SoC.
3.Modify annotation texts to be more in line with the current state.