Revert "locking/spinlock/debug: Remove spinlock lockup detection code"

This reverts commit c0c6dff9.

We cannot always rely upon NMI watchdog to help catch spinlock lockups.
Revert the change that removes __spinlock_debug as the benefits outweight
the potential false positives.

Change-Id: I58858c4a2443c0a6b209ea90545ebdbd72b3abfe
Signed-off-by: Kyle Yan <kyan@codeaurora.org>