x86/platform/uv/BAU: Fix HUB errors by remove initial write to sw-ack register

x86/platform/uv/BAU: Fix HUB errors by remove initial write to sw-ack register

Orabug: 25920237

Writing to the software acknowledge clear register when there are no
pending messages causes a HUB error to assert. The original intent of this
write was to clear the pending bits before start of operation, but this is
an incorrect method and has been determined to be unnecessary.

Signed-off-by: Andrew Banman <abanman@hpe.com>
Acked-by: Mike Travis <mike.travis@hpe.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: rja@hpe.com
Cc: sivanich@hpe.com
Link: http://lkml.kernel.org/r/1487351269-181133-1-git-send-email-abanman@hpe.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 1b17c6df852851b40c3c27c66b8fa2fd99cf25d8)
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>