nvme: fix nvme_pr_* status code parsing

Fix the parsing if extra status bits (e.g. MORE) is present.

Fixes: 7fb42780 ("nvme: Convert NVMe errors to PR errors")
Signed-off-by: Weiwen Hu <huweiwen@linux.alibaba.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>