PCI: use better error return values in aer_inject

Replaced some error return values in aer_inject. Use -ENODEV when we
can't find a device and -ENOTTY when the device does not support PCIe AER.

Acked-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>