dt-bindings: spi: sunxi: document F1C100 controllers

The Allwinner F1C100 series contains two SPI controllers, which are
compatible to the IP block used in the Allwinner H3 as well.
The only difference in the integration is the missing mod clock in the
F1C100, but that does not affect the SPI controller binding, as we can
still supply the correct clock (AHB parent) easily.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Samuel Holland <samuel@sholland.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220317162349.739636-11-andre.przywara@arm.com