qcacld-3.0: Avoid missing hidden AP when search scan db by ssid

Roam channel map is got by searching current ssid in scan db,
For hidden ssid, probe resp has ssid, but beacon usually has NULL
ssid. we'd better keep ssid from probe resp as long as possible,
don't override with NULL ssid from beacon as WIN's way.

Change-Id: Ia9295832926129a1f9f29785703d44e8268e750d
CRs-Fixed: 2427355

Kbuild

@@ -2656,7 +2656,7 @@ CONFIG_SCAN_MAX_SCAN_TIME ?= 30000
 ccflags-y += -DSCAN_MAX_SCAN_TIME=$(CONFIG_SCAN_MAX_SCAN_TIME)
 CONFIG_SCAN_NETWORK_IDLE_TIMEOUT ?= 0
 ccflags-y += -DSCAN_NETWORK_IDLE_TIMEOUT=$(CONFIG_SCAN_NETWORK_IDLE_TIMEOUT)
-CONFIG_HIDDEN_SSID_TIME ?= 1*60*1000
+CONFIG_HIDDEN_SSID_TIME ?= 0xFFFFFFFF
 ccflags-y += -DHIDDEN_SSID_TIME=$(CONFIG_HIDDEN_SSID_TIME)
 CONFIG_SCAN_CHAN_STATS_EVENT_ENAB ?= false
 ccflags-y += -DSCAN_CHAN_STATS_EVENT_ENAB=$(CONFIG_SCAN_CHAN_STATS_EVENT_ENAB)