fm10k: don't assume VLAN 1 is enabled

Since commit 856dfd69e84f ("fm10k: Fix multicast mode synch issues",
2016-03-03) we've incorrectly assumed that VLAN 1 is enabled when the
default VID is not set.

This occurs because we check the default_vid and if it's zero, start
several loops over the active_vlans bitmask at 1, instead of checking to
ensure that that bit is active.

This happened because of commit d9ff3ee8efe9 ("fm10k: Add support for
VLAN 0 w/o default VLAN", 2014-08-07) which mistakenly assumed that we
should send requests for MAC and VLAN filters with VLAN 0 when the
default_vid isn't set.

However, the switch generally considers this an invalid configuration,
so the only time we'd have a default_vid of 0 is when the switch is
down.

Instead, lets just not request any filters for the default_vid if it's
not yet been assigned.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>