nvme: copy firmware_rev on each init

stable inclusion
from stable-v4.19.262
commit 366a2b3110c69f919fb3277acc1a0bb8cd8a8dbd
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ZXGL


CVE: NA

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[ Upstream commit a8eb6c1b ]

The firmware revision can change on after a reset so copy the most
recent info each time instead of just the first time, otherwise the
sysfs firmware_rev entry may contain stale data.

Reported-by: Jeff Lien <jeff.lien@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Chao Leng <lengchao@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>