wifi: libertas: Fix possible refcount leak in if_usb_probe()

[ Upstream commit 6fd57e1d120bf13d4dc6c200a7cf914e6347a316 ]

usb_get_dev will be called before lbs_get_firmware_async which means that
usb_put_dev need to be called when lbs_get_firmware_async fails.

Fixes: ce84bb69 ("libertas USB: convert to asynchronous firmware loading")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220620092350.39960-1-hbh25y@gmail.com
Link: https://lore.kernel.org/r/20220622113402.16969-1-colin.i.king@gmail.com


Signed-off-by: Sasha Levin <sashal@kernel.org>