ixgbevf: Improve error handling in mailbox

Add new handling for error codes:
 IXGBE_ERR_CONFIG - ixgbe_mbx_operations is not correctly set
 IXGBE_ERR_TIMEOUT - mailbox operation, e.g. poll for message, timeout

Signed-off-by: Radoslaw Tyl <radoslawx.tyl@intel.com>
Tested-by: Tony Brelinski <tony.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>