x86/platform/uv: Fix kmalloc() NULL check routine

The result of kmalloc() should have been checked ahead of below statement:

	pqp = (struct bau_pq_entry *)vp;

Move BUG_ON(!vp) before above statement.

Signed-off-by: Austin Kim <austindh.kim@gmail.com>
Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Cc: Hedi Berriche <hedi.berriche@hpe.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <russ.anderson@hpe.com>
Cc: Steve Wahl <steve.wahl@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: allison@lohutok.net
Cc: andy@infradead.org
Cc: armijn@tjaldur.nl
Cc: bp@alien8.de
Cc: dvhart@infradead.org
Cc: gregkh@linuxfoundation.org
Cc: hpa@zytor.com
Cc: kjlu@umn.edu
Cc: platform-driver-x86@vger.kernel.org
Link: https://lkml.kernel.org/r/20190905232951.GA28779@LGEARND20B15


Signed-off-by: Ingo Molnar <mingo@kernel.org>