nvme-pci: factor out a nvme_pci_alloc_dev helper

stable inclusion
from stable-v5.10.198
commit 97e148dcb97d2b1fefedc83bbc2238dada68d224
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I987V5

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=97e148dcb97d2b1fefedc83bbc2238dada68d224



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[ Upstream commit 2e87570b ]

Add a helper that allocates the nvme_dev structure up to the point where
we can call nvme_init_ctrl.  This pairs with the free_ctrl method and can
thus be used to cleanup the teardown path and make it more symmetric.

Note that this now calls nvme_init_ctrl a lot earlier during probing,
which also means the per-controller character device shows up earlier.
Due to the controller state no commnds can be send on it, but it might
make sense to delay the cdev registration until nvme_init_ctrl_finish.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Tested-by Gerd Bayer <gbayer@linxu.ibm.com>
Stable-dep-of: dad651b2 ("nvme-pci: do not set the NUMA node of device if it has none")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>