dt-bindings: i2c: intel,ixp4xx-i2c: Convert to DT schema

dt-bindings: i2c: intel,ixp4xx-i2c: Convert to DT schema

Convert the IOP3xx and IXP4xx XScale bindings to DT schema. This
conversion also adds the interrupts property, as it is used by the driver
and existing DTS files but was not documented in the original binding.

Signed-off-by: Shi Hao <i.shihao.999@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260330054439.9545-1-i.shihao.999@gmail.com