spi: ingenic: Add support for use GPIO as chip select line.

Add support for using GPIOs as chip select lines on Ingenic SoCs.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/1650724725-93758-2-git-send-email-zhouyanjie@wanyeetech.com


Signed-off-by: Mark Brown <broonie@kernel.org>