wifi: mwifiex: Use default @max_active for workqueues

These workqueues only host a single work item and thus doen't need explicit
concurrency limit. Let's use the default @max_active. This doesn't cost
anything and clearly expresses that @max_active doesn't matter.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Acked-by: Kalle Valo <kvalo@kernel.org>
Cc: Amitkumar Karwar <amitkarwar@gmail.com>
Cc: Ganapathi Bhat <ganapathi017@gmail.com>
Cc: Sharvari Harisangam <sharvari.harisangam@nxp.com>
Cc: Xinming Hu <huxinming820@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org