wifi: rtw89: Add missing check for alloc_workqueue

wifi: rtw89: Add missing check for alloc_workqueue

[ Upstream commit 0046fa875b229a6c408ad4b2c6c9bc44d863e0b3 ]

Add check for the return value of alloc_workqueue since it may return
NULL pointer.
Moreover, add destroy_workqueue when rtw89_load_firmware fails.

Fixes: 9c5adf19c17c ("rtw89: add Realtek 802.11ax driver")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230104142901.1611-1-jiasheng@iscas.ac.cn
Signed-off-by: Sasha Levin <sashal@kernel.org>