ixgb: Add PCI Error recovery callbacks

Adds PCI Error recovery callbacks to the Intel 10-gigabit ethernet ixgb
device driver.  Lightly tested, works.

"Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:

Both pci_disable_device and ixgb_down would access the device.  It doesn't
follow Documentation/pci-error-recovery.txt that error_detected shouldn't do
any access to the device.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>