cw1200: fix missing destroy_workqueue() on error in cw1200_init_common

Add the missing destroy_workqueue() before return from
cw1200_init_common in the error handling case.

Fixes: a910e4a9 ("cw1200: add driver for the ST-E CW1100 & CW1200 WLAN chipsets")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201119070842.1011-1-miaoqinglang@huawei.com