brcmfmac: unbind all devices upon failure in firmware callback

When request firmware fails, brcmf_ops_sdio_remove is being called and
brcmf_bus freed. In such circumstancies if you do a suspend/resume cycle
the kernel hangs on resume due a NULL pointer dereference in resume
function. So in brcmf_sdio_firmware_callback() we need to unbind the
driver from both sdio_func devices when firmware load failure is indicated.

Cc: stable@vger.kernel.org # 4.9.x-
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>