Remove lport from net device and then do synchronize net device to flush
inflight rx frames for the lport before doing fcoe_percpu_clean.

In case of master lport, remove all rx packet handlers completely and
then only do fcoe_percpu_clean. This required splitting fcoe_interface_cleanup
to do remove part separately and for that added func fcoe_interface_remove
and then  call it from fcoe_if_destory before doing fcoe_percpu_clean.
However if fcoe_interface_remove() is already called then
don't call again from fcoe_interface_cleanup() to preserve its
existing flows.

This patch along with Neil's other patch to avoid soft irq context
on ingress will avoid passing up frames on disabled lport as
discussed in this mail thread:-
http://lists.open-fcoe.org/pipermail/devel/2012-February/011947.htmlSigned-off-by: Vasu Dev <vasu.dev@intel.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>