x86, UV: Correct BAU software acknowledge

Correct the acknowledgment and the reset of a BAU
software-acknowledged message.

A retry message should be testing only for timed-out resources
(mask << 8). (And we delete a log message that might cause
unnecessary concern) The acknowledge MMR is
|--timed-out--|---pending--|,  each is 8 bits.

The IPI-driven reset of software acknowledge resources frees
both timed out and pending resources.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: gregkh@suse.de
LKML-Reference: <E1OJvNy-0004aP-7O@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>