vlan: conditional inclusion of FCoE hooks to match netdevice.h and bnx2x

Way back in 3c9c36bc the
ndo_fcoe_get_wwn pointer was switched from depending on CONFIG_FCOE to
CONFIG_LIBFCOE in order to allow building FCoE support into the bnx2x
driver and used by bnx2fc without including the generic software fcoe
module.

But, FCoE is generally used over an 802.1q VLAN, and the implementation
of ndo_fcoe_get_wwn in the 8021q module was not similarly changed.  The
result is that if CONFIG_FCOE is disabled, then bnz2fc cannot make a
call to ndo_fcoe_get_wwn through the 8021q interface to the underlying
bnx2x interface.  The bnx2fc driver then falls back to a potentially
different mapping of Ethernet MAC to Fibre Channel WWN, creating an
incompatibility with the fabric and target configurations when compared
to the WWNs used by pre-boot firmware and differently-configured
kernels.

So make the conditional inclusion of FCoE code in 8021q match the
conditional inclusion in netdevice.h

Signed-off-by: Chris Leech <cleech@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>