net: dcbnl: check correct ops in dcbnl_ieee_set()

The incorrect ops routine was being tested for in
DCB_ATTR_IEEE_PFC attributes. This patch corrects
it.

Currently, every driver implementing ieee_setets also
implements ieee_setpfc so this bug is not actualized
yet.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>