brcmfmac: restore stopping netdev queue when bus clogs up

When the host-interface bus has hard time handling transmit packets
it informs higher layer about this and it would stop the netdev
queue when needed. However, since commit 9cd18359 ("brcmfmac:
Make FWS queueing configurable.") this was broken. With this patch
the behaviour is restored.

Cc: stable@vger.kernel.org # v4.5, v4.6, v4.7
Fixes: 9cd18359 ("brcmfmac: Make FWS queueing configurable.")
Tested-by: Per Förlin <per.forlin@gmail.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>