arch: arm: tegratab: Set poweron_lpk to restart.

By long press key, the system need to be restarted
instead of power off.

bug 1308187

Change-Id: Ib570f2c6f51eb8fe40990e0022e788e90f84e889
Signed-off-by: Harry Hong <hhong@nvidia.com>
Reviewed-on: http://git-master/r/239622
(cherry picked from commit 996d8c3e9a2889f86f701c48775b27fce69a7389)
Reviewed-on: http://git-master/r/288789
Reviewed-by: Peter Kim <pekim@nvidia.com>
Tested-by: Peter Kim <pekim@nvidia.com>