platform/x86: barco-p50-gpio: use KEY_VENDOR for button instead of KEY_RESTART

It turns out that systemd-logind by default listens for KEY_RESTART input
events and reboots the machine, which isn't great - So use KEY_VENDOR for
the vendor specific identify button instead to not conflict.

Signed-off-by: Peter Korsgaard <peter.korsgaard@barco.com>
Link: https://lore.kernel.org/r/20211022124612.19780-1-peter@korsgaard.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>