currently /proc/ide/HWIF are created in one shot during initialization
or in ide-generic meaning that for modular IDE you must include
ide-generic.

this adds per-hwif registration currently for PCI only (that is what I
can test); if this is OK I will make create_proc_ide_interfaces static
and replace it with create_proc_ide_interface where appropriate.

this also makes /proc/ide entries for PCI chipset be correctly created

-andrey