qed: Remove unused data member 'is_mf_default'.

The data member 'is_mf_default' is not used by the qed/qede drivers,
removing the same.

Signed-off-by: Sudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>