x86/platform/uv/BAU: Clean up pq_init()

x86/platform/uv/BAU: Clean up pq_init()

Orabug: 25477822

The payload queue first MMR requires the physical memory address and hub
GNODE of where the payload queue resides in memory, but the associated
variables are named as if the PNODE were used. Rename gnode-related
variables and clarify the definitions of the payload queue head, last, and
tail pointers.

Signed-off-by: Andrew Banman <abanman@sgi.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mike Travis <travis@sgi.com>
Acked-by: Dimitri Sivanich <sivanich@sgi.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: akpm@linux-foundation.org
Cc: rja@sgi.com
Link: http://lkml.kernel.org/r/1474474161-265604-4-git-send-email-abanman@sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit d2a57afa53f3fdf9f68d1f4240ace85a7d20ca20)
Signed-off-by: Brian Maly <brian.maly@oracle.com>