brcmfmac: disable MBSS feature for BCM43362

The BCM43362 firmware falsely reports it is capable of providing
MBSS. As a result AP mode no longer works for this device. Therefor
disable MBSS in the driver for this chipset.

Cc: stable@vger.kernel.org # 3.19.y
Reported-by: Jorg Krause <jkrause@posteo.de>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>