qcacld-3.0: Disable adaptive dwell scan for Roaming by default

1. There is a need for STA to find better AP to connect to, so
this becomes priority over total scan duration.
2. Typically there are very few channel numbers to scan (with FW
CHAN MAP) therefore any penalty with higher dwell time is
compensated with the lesser number of channel. Only in case of
not finding a candidate FW does full scan but that probability
might reduce if AP is found in first CHAN map scan.

Change-Id: Ib923c2af9b92a1465730a861a2b56393dc3d8668
CRs-Fixed: 2431846

components/mlme/dispatcher/inc/cfg_mlme_lfr.h

@@ -535,7 +535,7 @@
  * roamscan_adaptive_dwell_mode - Sets dwell time adaptive mode
  * @Min: 0
  * @Max: 4
- * @Default: 1
+ * @Default: 4
  *
  * This parameter will set the algo used in dwell time optimization during
  * roam scan. see enum scan_dwelltime_adaptive_mode.
@@ -558,7 +558,7 @@
 	"roamscan_adaptive_dwell_mode", \
 	0, \
 	4, \
-	1, \
+	4, \
 	CFG_VALUE_OR_DEFAULT, \
 	"Sets dwell time adaptive mode")