PCI/ASPM: Factor out pcie_wait_for_retrain()

stable inclusion
from stable-v5.10.190
commit 9f283ca643ddce6d7580780d7421ec80db59f9c2
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I928UI

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9f283ca643ddce6d7580780d7421ec80db59f9c2



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[ Upstream commit 9c7f1364 ]

Factor pcie_wait_for_retrain() out from pcie_retrain_link().  No functional
change intended.

[bhelgaas: split out from
https: //lore.kernel.org/r/20230502083923.34562-1-ilpo.jarvinen@linux.intel.com]
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Stable-dep-of: e7e39756 ("PCI/ASPM: Avoid link retraining race")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>