wilc1000: call complete() for failure in wilc_wlan_txq_add_cfg_pkt()

Added complete() call for failure case in wilc_wlan_txq_add_cfg_pkt().

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201125114059.10006-5-ajay.kathat@microchip.com