dt-bindings: mfd: Add bindings for AXP192 MFD device

The AXP192 PMIC is similar to the AXP202/AXP209, but with different
regulators, additional GPIOs, and a different IRQ register layout,
so it needs a new compatible string.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230511092609.76183-2-aidanmacdonald.0x0@gmail.com


Signed-off-by: Lee Jones <lee@kernel.org>