wifi: mac80211: Don't call fq_flow_idx() for management frames

skb_get_hash() can only be used when the skb is linked to a netdev
device.

Signed-off-by: Alexander Wetzel <Alexander@wetzel-home.de>
Fixes: 73bc9e0a ("mac80211: don't apply flow control on management frames")
Link: https://patch.msgid.link/20250717162547.94582-3-Alexander@wetzel-home.de


Signed-off-by: Johannes Berg <johannes.berg@intel.com>