brcmfmac: on sdio remove first detach bus then stop worker.

brcmfmac: on sdio remove first detach bus then stop worker.

Currently the function sdio_remove will first destroy the datawork
workqueue and then detach the bus. This can create the situation
where work gets added on non-existing work queue resulting in panic.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Daniel (Deognyoun) Kim <dekim@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>