qcacld-3.0: Introduce WLAN_DBGLOG_DEBUGFS feature flag

Currently the Debug Log DebugFS functionality in the qca-wifi-host-cmn
project is protected with #ifdef WLAN_OPEN_SOURCE.

The WLAN_OPEN_SOURCE macro was introduced for a legacy reason that is
no longer applicable. In order to remove the WLAN_OPEN_SOURCE macro,
introduce a new feature-specific WLAN_DBGLOG_DEBUGFS feature flag.
Once the Debug Log DebugFS functionality moves to the new flag, the
WLAN_OPEN_SOURCE macro can be removed.

Change-Id: I159af54ab91d009e5bf50d67492cbc62a05bad47
CRs-Fixed: 3463793

Kbuild

@@ -4260,6 +4260,7 @@ ccflags-$(CONFIG_WLAN_DFS_MASTER_ENABLE) += -DQCA_DFS_NOL_PLATFORM_DRV_SUPPORT
 ccflags-$(CONFIG_QCA_DFS_BW_PUNCTURE) += -DQCA_DFS_BW_PUNCTURE
 
 ccflags-$(CONFIG_WLAN_DEBUGFS) += -DWLAN_DEBUGFS
+ccflags-$(CONFIG_WLAN_DEBUGFS) += -DWLAN_DBGLOG_DEBUGFS
 ccflags-$(CONFIG_WLAN_STREAMFS) += -DWLAN_STREAMFS
 
 ccflags-$(CONFIG_DYNAMIC_DEBUG) += -DFEATURE_MULTICAST_HOST_FW_MSGS