qcacld-3.0: Fix uninitialized SWLM timer deletion

Currently if SWLM is disabled then SWLM based flush timer will
not be initialiazed, but during cleanup path timer deletion is called.

Fix is to check SWLM enablement before deleting flush timer.

Change-Id: I12a4c62bdda35854230de02248f55892dcf5caa2
CRs-Fixed: 3184918

core/dp/txrx3.0/dp_swlm.c

@@ -287,6 +287,9 @@ QDF_STATUS dp_soc_swlm_detach(struct dp_soc *soc)
 	QDF_STATUS ret;
 	int i;
 
+	if (!swlm->is_enabled)
+		return QDF_STATUS_SUCCESS;
+
 	swlm->is_enabled = false;
 
 	for (i = 0; i < soc->num_tcl_data_rings; i++) {