wifi: libertas: add missing calls to cancel_work_sync()

Add missing 'cancel_work_sync()' in 'if_sdio_remove()'
and on error handling path in 'if_sdio_probe()'.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Tested-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230725060531.72968-1-dmantipov@yandex.ru