dt-bindings: gpio: mpfs-gpio: permit resets

Both CoreGPIO and the hardened versions of it on mpfs and pic64gx have a
reset pin. For the former, usually this is wired to a common fabric
reset not managed by software and for the latter two the platform
firmware takes them out of reset on first-party boards (or those using
modified versions of the vendor firmware), but not all boards may take
this approach. Permit providing a reset in devicetree for Linux, or
other devicetree-consuming software, to use.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20260303-irate-hungry-b54cda817e42@spud
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>