brcmfmac: change driver unbind order of the sdio function devices

In the function brcmf_sdio_firmware_callback() the driver is
unbound from the sdio function devices in the error path.
However, the order in which it is done resulted in a use-after-free
issue (see brcmf_ops_sdio_remove() in bcmsdh.c). Hence change
the order and first unbind sdio function #2 device and then
unbind sdio function #1 device.

Cc: stable@vger.kernel.org # v4.12.x
Fixes: 7a51461f ("brcmfmac: unbind all devices upon failure in firmware callback")
Reported-by: Stefan Wahren <stefan.wahren@i2se.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>