kvm: ensure hard lockup detection is disabled by default

Use watchdog_enable_hardlockup_detector() to set hard lockup detection's
default value to false.  It's risky to run this detection in a guest, as
false positives are easy to trigger, especially if the host is
overcommitted.

Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>