At run-time, if softlockup_thresh is changed to a much lower value,
touch_timestamp is likely to be much older than the new softlock_thresh.

This will cause a false softlockup to be detected. If softlockup_panic
is enabled, the system will panic.

The fix is to touch all watchdogs before changing softlockup_thresh.
Signed-off-by: NMandeep Singh Baines <msb@google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>