regulator: dt-bindings: Convert ltc3589.txt to yaml format

Convert ltc3589.txt to yaml format.

Additional changes:
- Add interrupts to match driver code
- Require lltc,fb-voltage-divider property ^(sw1|sw2|sw3|bb-out|ldo1|ldo2)$

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260714160147.1641379-1-Frank.Li@oss.nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>