mwifiex: Fix issue in the SDIO reset path of mwifiex.

SDIO reset was not happening properly on mwifiex as cancel_work_sync
in mwifiex_sdio_remove used to kill the calling work function itself.
Due to this, the interface was not getting removed and card was not
getting added again. Reset work function has been made independent
of adapter variable and cancel_work_sync has been moved to cleanup
function.

Signed-off-by: Maithili Hinge <maithili@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>