nl80211: Fix sending proper VLAN ID attr value when using VLAN offload

nl80211: Fix sending proper VLAN ID attr value when using VLAN offload

The NL80211_ATTR_VLAN_ID attribute expects non-zero values, but vlan_id
with value 0 has been set in VLAN offload case. Due to this, station
connection failure is observed if the driver advertises VLAN_OFFLOAD
support:

nl80211: NL80211_ATTR_STA_VLAN (addr=8c:fd:f0:22:19:15 ifname=wlan0
         vlan_id=0) failed: -34 (Result not representable)
wlan0: STA 8c:fd:f0:22:19:15 IEEE 802.11: could not bind the STA
         entry to vlan_id=0

Fix this by setting only non-zero values.

Fixes: 0f903f37dca1 ("nl80211: VLAN offload support")
Signed-off-by: Seevalamuthu Mariappan <seevalam@codeaurora.org>