pinctrl: bcm281xx: Provide pinctrl device info as OF platform data

Introduce a new struct type, "bcm281xx_pinctrl_info", that holds
information about the pins, pin functions and regmap config for a pin
control chip. Create such a struct for the BCM218xx and pass it as
device data for the OF compatible match.

This is done in preparation for introducing additional chip types
to the driver.

Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
Link: https://lore.kernel.org/20250303-bcm21664-pinctrl-v3-3-5f8b80e4ab51@gmail.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>