arm64: tegra: Redefine force recovery key on Jetson AGX Xavier

The current BTN_1 code associated with the force-recovery key is not a
valid code for EV_KEY type input devices. This causes errors in the
libinput debug-events command.

There is no system level action that maps to the force-recovery key on
Jetson AGX Xavier, so assign it the KEY_SLEEP action, which at least
makes it do something marginally useful.

Signed-off-by: Thierry Reding <treding@nvidia.com>