qlcnic: fix mac override capability

o Rename mac_learning to mac_override
o Added check in set_mac to return error if mac override is disabled.
o Disabling mac_override only supported for Non priviledged functions.

Signed-off-by: Rajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>