qlcnic: Disable DCB operations from SR-IOV VFs.

o These operations will be supported only through PFs (SR-IOV and non-SR-IOV).

Signed-off-by: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>