dt-bindings: i2c: mv64xxx: Add F1C100s compatible string

The I2C controller IP used in the Allwinner F1C100s series of SoCs is
compatible with the ones used in the other Allwinner SoCs.

Add an F1C100s specific compatible string to the list of existing names.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>