x86, UV: Correct BAU regular message type

The Broadcast Assist Unit messages have a regular or retry
message type. The regular type was not being set, but needs to
be, because the lack of a message type is sometimes used to
identify an unused entry in the message queue.
Also removing some excess comments.

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