realtek: netgear-gigabit: Add gpio-restart node

realtek: netgear-gigabit: Add gpio-restart node

The Netgear GS110TPP v1 switch cannot reliably perform cold reboots
using the system's internal reset controller.

On this device, and the other supported Netgear switches, internal GPIO
line 13 is connected to the system's hard reset logic. Expose this GPIO
on all systems to ensure restarts work properly.

Cc: Raylynn Knight <rayknight@me.com>
Cc: Michael Mohr <akihana@gmail.com>
Cc: Stijn Segers <foss@volatilesystems.org>
Cc: Stijn Tintel <stijn@linux-ipv6.be>
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Tested-by: Bjørn Mork <bjorn@mork.no>