pci: New PCI-E reset API

Adds a new API which can be used to issue various types
of PCI-E reset, including PCI-E warm reset and PCI-E hot reset.
This is needed for an ipr PCI-E adapter which does not properly
implement BIST. Running BIST on this adapter results in PCI-E
errors. The only reliable reset mechanism that exists on this
hardware is PCI Fundamental reset (warm reset). Since driving
this type of reset is architecture unique, this provides the
necessary hooks for architectures to add this support.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Acked-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>