dt-bindings: mfd: Convert zii,rave-sp.txt to yaml format

Convert device binding doc zii,rave-sp.txt to yaml format.
Additional change:
- ref to other zii yaml files.
- remove rave-sp-hwmon and rave-sp-leds.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20241010-zii_yaml-v2-5-0ab730607422@nxp.com


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