usb: fix defined but not used warnings in hcd-pci.c

Shows up on ia64 builds (and possibly elsewhere) for configs that
don't set PM_RUNTIME or PM_SLEEP as follows:

drivers/usb/core/hcd-pci.c:383:12: warning: 'suspend_common' defined but not used
drivers/usb/core/hcd-pci.c:438:12: warning: 'resume_common' defined but not used

As per above, the functions are only used if RUNTIME/SLEEP are set,
so make the two functions conditional on these Kconfig values.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>