PCI/portdrv: Encapsulate pcie_ports_auto inside the port driver

"pcie_ports_auto" is only used inside the PCIe port driver itself, so
move it from include/linux/pci.h to portdrv.h so it's not visible to the
whole kernel.

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

drivers/pci/pcie/portdrv.h

@@ -12,6 +12,8 @@
 
 #include <linux/compiler.h>
 
+extern bool pcie_ports_auto;
+
 /* Service Type */
 #define PCIE_PORT_SERVICE_PME_SHIFT	0	/* Power Management Event */
 #define PCIE_PORT_SERVICE_PME		(1 << PCIE_PORT_SERVICE_PME_SHIFT)