PCI: Handle FLR failure and allow other reset types

pci_flr_wait() and pci_af_flr() functions assume graceful return even
though the device is inaccessible under error conditions.

Return -ENOTTY in error cases so that __pci_reset_function_locked() can
try other reset types if AF_FLR/FLR reset fails.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>