bnx2x: Remove configured vlans as part of unload sequence.

Vlans are not getting removed when drivers are unloaded. The recent storm
firmware versions had added safeguards against re-configuring an already
configured vlan. As a result, PF inner reload flows (e.g., mtu change)
might trigger an assertion.
This change is going to remove vlans (same as we do for MACs) when doing
a chip cleanup during unload.

Signed-off-by: Sudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>