qlge: Fix qlge_update_hw_vlan_features to handle if interface is down

Currently qlge_update_hw_vlan_features() will always first put the
interface down, then update features and then bring it up again. But it
is possible to hit this code while the adapter is down and this causes a
non-paired call to napi_disable(), which will get stuck.

This patch fixes it by skipping these down/up actions if the interface
is already down.

Fixes: a45adbe8 ("qlge: Enhance nested VLAN (Q-in-Q) handling.")
Cc: Harish Patil <harish.patil@qlogic.com>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>