scsi: hpsa: correct device resets

Correct a race condition that occurs between the reset handler and the
completion handler. There are times when the wait_event condition is
never met due to this race condition and the reset never completes.

The reset_pending field is NULL initially.

  t  Reset Handler Thread     Completion Thread
  -- --------------------     -----------------
  t1                          if (c->reset_pending)
  t2 c->reset_pending = dev;     if (atomic_dev_and_test(counter))
  t3 atomic_inc(counter)             wait_up_all(event_sync_wait_queue)
  t4
  t5 wait_event(...counter == 0)

Kernel.org Bugzilla:
           https://bugzilla.kernel.org/show_bug.cgi?id=1994350


           Bug 199435 - HPSA + P420i resetting logical Direct-Access
                        never complete

Reviewed-by: Justin Lindley <justin.lindley@microsemi.com>
Reviewed-by: David Carroll <david.carroll@microsemi.com>
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>