PCI: Replace strict_strtoul() with kstrtoul()

The usage of strict_strtoul() is not preferred, because
strict_strtoul() is obsolete.  Thus, kstrtoul() should be
used.

[bhelgaas: "#define strict_strtoul  kstrtoul", so no functional change]
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>