brcmfmac: fix uninitialized field in scheduled scan ssid configuration

The scheduled scan ssid configuration in firmware has a flags field that
was not initialized resulting in unexpected behaviour.

Fixes: e3bdb7cc0300 ("brcmfmac: fix handling ssids in .sched_scan_start() callback")
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>