PCI: Clean up resource_alignment parameter to not require static buffer

Clean up the 'resource_alignment' parameter code to use kstrdup() in the
initcall routine instead of a static buffer that wastes memory regardless
of whether the feature is used.  This allows us to drop 'COMMAND_LINE_SIZE'
bytes (typically 256-4096 depending on architecture) of static data.

This is similar to what has been done for the 'disable_acs_redir'
parameter.

Link: https://lore.kernel.org/r/20190822161013.5481-2-logang@deltatee.com


Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>