Clean up watchdog reset code:
 - move code that checks for stuck slice to a common routine
 - unless there is a confirmed h/w fault, verify that a stuck
   slice is still stuck in the watchdog worker; if the slice is no
   longer stuck, abort the reset.
 - this removes an egregious 2000ms pause in the watchdog worker that
   was a diagnostic aid (to look for spurious resets) the snuck into
   production code.

v3 includes corrections from Joe Perches
Signed-off-by: Jon Mason <mason@myri.com>
Signed-off-by: David S. Miller <davem@davemloft.net>