Allwinner A31 has introduced a new memory mapping and a
reset line.

The difference in memory mapping are :

- In the configure register there is a new sample bit
  and Allwinner has introduced the active threshold feature.

- In the status register a new STAT bit is present.

Note: CGPO and DRQ_EN bits are removed on A31 but present on A13
and on new SoCs like A64/H6.
This is actually not an issue as these bits are togglable and new
SoCs have a dedicated bindings.

Introduce this bindings to make a difference since this generation.
And declare the reset line required since A31.
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>