PCI/ASPM: Remove struct aspm_latency

The struct aspm_latency is now used only inside pcie_aspm_check_latency().

Replace struct aspm_latency variables with u32 variables and remove struct
aspm_latency.

Link: https://lore.kernel.org/r/20211119193732.12343-5-refactormyself@gmail.com


Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>