qlcnic: Use generic fdb handler when driver options are not enabled.

Allow qlcnic to use the generic fdb handler when the driver options
are not enabled.   Untill the driver is fully fixed, this allows
the use of the FDB interface with qlogic driver, but simply puts
the driver into promisc mode since the driver currently does not
support IFF_UNICAST_FLT.

CC: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Acked-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
CC: Sony Chacko <sony.chacko@qlogic.com>
CC: linux-driver@qlogic.com
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>