module/scmi_pinctrl: Fix multiple bugs and improve validation

This patch addresses several issues in the `scmi_pinctrl` and `pictrl` module.
The following bugs have been fixed:
- Update message_attribute command.
- Solve scmi_pin_control bug in list_association.
- Solve scmi_pin_control bug in get_setting.
- Remove unimplemented protocols from scmi_pin_control.
- Update scmi_pin_control payload size table.
- Update the scmi_validation check to ignore variable length payload messages.
- Update the MOD_PIN_CONTROL_API to MOD_PINCTRL_API_IDX.

Signed-off-by: Khaled Ali Ahmed <khaled.aliahmed@arm.com>