When an skb is shared, it needs to be duplicated, along with its data buffer.
If the skb does not have enough headroom, using skb_copy might cause the data
buffer to be copied twice (once by skb_copy and once by pskb_expand_head).
Fix this by using skb_clone initially and letting ieee80211_skb_resize sort
out the rest.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>