staging: wfx: fix potential use-after-free

wfx_tx_policy_put() use data from the skb. However, the call to
skb_pull() has just discarded them (even if the memory is in fact not
really discarded).

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200515083325.378539-11-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>