wifi: brcmfmac: Fix to add skb free for TIM update info when tx is completed

The skb will be allocated to send TIM update info in brcmf_fws_tim_update.
Currently the skb will be freed when tx is failed but it will not be freed
when tx is completed successfully. The fix is to free the skb when tx is
completed always.

Signed-off-by: Wataru Gohda <wataru.gohda@cypress.com>
Signed-off-by: Chi-hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220722115632.620681-6-alvin@pqrs.dk