PCI: hotplug: Make core explicitly non-modular

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

  obj-$(CONFIG_HOTPLUG_PCI)           += pci_hotplug.o
  [...]
  pci_hotplug-objs                    := pci_hotplug_core.o

  drivers/pci/hotplug/Kconfig:menuconfig HOTPLUG_PCI
  drivers/pci/hotplug/Kconfig:  bool "Support for PCI Hotplug"

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.

Remove orphaned exit function in cpci_hotplug_core.c.

Note that for non-modular code, module_init() translates to
device_initcall().  One could argue that we should use subsys_initcall()
here, but for now we stick with runtime equivalence.

We would delete module.h and just keep the moduleparam.h include (since the
file does use module_param), but there is a try_module_get and module_put
pairing that prevents us from doing that.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Scott Murray <scott@spiteful.org>
CC: Kristen Carlson Accardi <kristen@linux.intel.com>