PCI: Use "unsigned long" for __pci_enable_device_flags to match ioport.h

__pci_enable_device_flags() takes values like IORESOURCE_IO and
IORESOURCE_MEM, which are values for struct resource.flags, which is
"unsigned long", not "resource_size_t".

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>