x86, UV: Correct UV2 BAU destination timeout

x86, UV: Correct UV2 BAU destination timeout

Correct the UV2 broacast assist unit's destination timeout
period. And the activation status register in UV2 should be
tested for a destination timeout with a 4, not a 2.  The values
for Active versus Timeout were reversed.

This patch is critical for TLB shootdown on an Altix UV2 system
(i.e. the follow-on to the current Altix UV).

 Destination timeout period:
  The period is set in 4 bits of memory-mapped register MISC_CONTROL.
  The left bit toggles base period between 10us and 80us.
  The other 3 bits are the multiplier.
 Decimal 15, hex f, gives the maximum: 7 * 80us

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Link: http://lkml.kernel.org/r/20110621122243.117324443@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>