mwifiex: avoid queue_work while work is ongoing

Current code does not check whether main_work_queue or
rx_work_queue is running when preparing to do queue_work,
this code fix add check before calling queue_work, reducing
unnecessary queue_work switch.

This change instead sets more_task flag to ensure we run main_process
superloop once again.

Signed-off-by: Shengzhen Li <szli@marvell.com>
Signed-off-by: Zhaoyang Liu <liuzy@marvell.com>
Reviewed-by: Cathy Luo <cluo@marvell.com>
Reviewed-by: Amitkumar Karwar <akarwar@marvell.com>
Reviewed-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>