be2net: Fix to not set link speed for disabled functions of a UMC card

This renders the interface view somewhat inconsistent from the Host OS POV
considering the rest of the interfaces are showing their respective speeds
based on the bandwidth assigned to them.

Signed-off-by: Somnath Kotur <somnath.kotur@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>