[SCSI] fcoe: fix offload feature flag change from netdev

Currently, when FCoE netdev feature flags are toggled by the LLD, lport's
corresponding flags are not updated. This causes the fc_fcp to still try to
offload the I/O. This patch adds support of NETDEV_FEAT_CHANGE event in fcoe
netdev device notification callback so we can update the lport offload flags
appropriately.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>