[PATCH] PCI: don't override drv->shutdown unconditionally

There are many drivers that have been setting the generic driver
model level shutdown callback, and pci thus must not override it.

Without this patch we can have really bad data loss on various
raid controllers.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>