PCI: Force trailing new line to resource_alignment_param in sysfs

PCI: Force trailing new line to resource_alignment_param in sysfs

When 'pci=resource_alignment=' is specified on the command line, there is
no trailing new line.  Then, when it's read through the corresponding sysfs
attribute, there will be no newline and a cat command will not show
correctly in a shell. If the parameter is set through sysfs a new line will
be stored and it will 'cat' correctly.

To solve this, append a new line character in the show function if one does
not already exist.

Link: https://lore.kernel.org/r/20190822161013.5481-4-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>