nvme-core: remove extra condition for vwc

In nvme_set_queue_limits() we initialize vwc to false and later add
a condition to set vwc true. The value of the vwc can be declare
initialized which makes all the blk_queue_XXX() calls uniform.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>