nvme: add new line after variable declatation

Add a new line in functions nvme_pr_preempt(), nvme_pr_clear(), and
nvme_pr_release() after variable declaration which follows the rest of
the code in the nvme/host/core.c.

No functional change(s) in this patch.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>