ARM: dts: microchip: change to simple-mfd from simple-bus for PIO3 pinumux controller

ARM: dts: microchip: change to simple-mfd from simple-bus for PIO3 pinumux controller

The pinctrl subnodes that define the pin configuration of other devices
under PIO3 pinmux controller are not simple memory mapped nodes.Ergo,
change simple-bus to simple-mfd.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240814061315.112564-2-manikandan.m@microchip.com
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>