dt-bindings: mfd: Convert twl-family.txt to json-schema

Convert the TWL[46]030 binding to DT schema format. To do it as a step by
step work, do not include / handle nodes for subdevices yet, just convert
things with minimal corrections. There are already some bindings for its
subdevices in the tree.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230916100515.1650336-2-andreas@kemnade.info


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