pch_phub: use module_pci_driver

this driver's pch_phub_pci_init, and pch_phub_pci_exit functions with
the module_init and module_exit calls can be replaced with
module_pci_driver

Signed-off-by: Devendra Naga <develkernel412222@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>