ARM: dts: Add strict_gpiod dtparam

Setting strict_gpiod disables the GPIO output persistence, such that
pins are returned to being inputs when they are released. Note that
this applies to the GPIO/pinctrl driver for the user-facing GPIOs,
not the SoC GPIOs on Pi 5.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>