PCI/portdrv: Remove unnecessary "pcie_ports=auto" parameter

The "pcie_ports=auto" parameter set pcie_ports_disabled and pcie_ports_auto
to their compiled-in defaults, so specifying the parameter is the same as
not using it at all.

Remove the "pcie_ports=auto" parameter and update the documentation.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Documentation/admin-guide/kernel-parameters.txt

@@ -3130,14 +3130,13 @@
 		force	Enable ASPM even on devices that claim not to support it.
 			WARNING: Forcing ASPM on may cause system lockups.
 
-	pcie_ports=	[PCIE] PCIe ports handling:
-		auto	Ask the BIOS whether or not to use native PCIe services
-			associated with PCIe ports (PME, hot-plug, AER).  Use
-			them only if that is allowed by the BIOS.
-		native	Use native PCIe services associated with PCIe ports
-			unconditionally.
-		compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
-			ports driver.
+	pcie_ports=	[PCIE] PCIe port services handling:
+		native	Use native PCIe services (PME, AER, DPC, PCIe hotplug)
+			even if the platform doesn't give the OS permission to
+			use them.  This may cause conflicts if the platform
+			also tries to use these services.
+		compat	Disable native PCIe services (PME, AER, DPC, PCIe
+			hotplug).
 
 	pcie_port_pm=	[PCIE] PCIe port power management handling:
 		off	Disable power management of all PCIe ports

drivers/pci/pcie/portdrv_pci.c

@@ -37,9 +37,6 @@ static int __init pcie_port_setup(char *str)
 	} else if (!strncmp(str, "native", 6)) {
 		pcie_ports_disabled = false;
 		pcie_ports_auto = false;
-	} else if (!strncmp(str, "auto", 4)) {
-		pcie_ports_disabled = false;
-		pcie_ports_auto = true;
 	}
 
 	return 1;