[SCSI] mpt2sas: Added support for PCIe Advanced Error Recovery.

Added support in the driver to support EEH and
PCIe Advanced Error Recovery. This involves adding new
pci_error_handler interface for recovering the controller from PCI Bus
errors, such as SERR and PERR. Some tools are available for simulating
PCI errors in order to validate this interface:
http://www.kernel.org/pub/linux/utils/pci/aer-inject



Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>