brcmfmac: setup passive scan if requested by user-space

The driver was not properly configuring firmware with regard to the
type of scan. It always performed an active scan even when user-space
was requesting for passive scan, ie. the scan request was done without
any SSIDs specified.

Cc: stable@vger.kernel.org # v4.0.x
Reported-by: Huang, Jiangyang <Jiangyang.Huang@itron.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>