wl12xx: fix wl12xx_scan_sched_scan_ssid_list() check that all given ssids are in filters

A minor fix for the check that verifies that all given SSIDs (in req) exist
in the filters (the match sets)

Signed-off-by: Eyal Shapira <eyal@wizery.com>
Acked-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>