x86/platform/uv/BAU: Add status mmr location fields to bau_control

x86/platform/uv/BAU: Add status mmr location fields to bau_control

The location of the ERROR and BUSY status bits depends on the descriptor
index, i.e. the CPU, of the message. Since this index does not change,
there is no need to calculate the mmr and index location during message
processing. The less work we do in the hot path the better.

Add status_mmr and status_index fields to bau_control and compute their
values during initialization. Add kerneldoc descriptions for the new
fields. Update uv*_wait_completion to use these fields rather than
receiving the information as parameters.

Signed-off-by: Andrew Banman <abanman@hpe.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mike Travis <mike.travis@hpe.com>
Cc: sivanich@hpe.com
Cc: rja@hpe.com
Cc: akpm@linux-foundation.org
Link: http://lkml.kernel.org/r/1489077734-111753-5-git-send-email-abanman@hpe.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>