PCI: Make DPC explicitly non-modular

This code is not being built as a module by anyone:

  drivers/pci/pcie/Kconfig:config PCIE_DPC
  drivers/pci/pcie/Kconfig:  bool "PCIe Downstream Port Containment support"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, module_init() translates to
device_initcall().

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Keith Busch <keith.busch@intel.com>
CC: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/pci/pcie/pcie-dpc.c

 /*
  * PCI Express Downstream Port Containment services driver
+ * Author: Keith Busch <keith.busch@intel.com>
+ *
  * Copyright (C) 2016 Intel Corp.
  *
  * This file is subject to the terms and conditions of the GNU General Public
@@ -9,7 +11,7 @@
 
 #include <linux/delay.h>
 #include <linux/interrupt.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/pci.h>
 #include <linux/pcieport_if.h>
 
@@ -143,16 +145,4 @@ static int __init dpc_service_init(void)
 {
 	return pcie_port_service_register(&dpcdriver);
 }
-
-static void __exit dpc_service_exit(void)
-{
-	pcie_port_service_unregister(&dpcdriver);
-}
-
-MODULE_DESCRIPTION("PCI Express Downstream Port Containment driver");
-MODULE_AUTHOR("Keith Busch <keith.busch@intel.com>");
-MODULE_LICENSE("GPL");
-MODULE_VERSION("0.1");
-
-module_init(dpc_service_init);
-module_exit(dpc_service_exit);
+device_initcall(dpc_service_init);