qcacmn: Sanity Check to avoid NULL pointer dereference

If module is not registered for dbr in any platform it
results into  Null pointer dereference.

Added Sanity check to avoid Null pointer dereference for
cfg80211tool wifi0 g_dbr_ring_status.

Change-Id: I9e68dfc9d58d70693184f53913cd7f2324d788c1

target_if/direct_buf_rx/src/target_if_direct_buf_rx_main.c

@@ -2084,6 +2084,13 @@ QDF_STATUS target_if_direct_buf_rx_print_ring_stat(
 			mod_param =
 				&dbr_pdev_obj->dbr_mod_param[mod_idx][srng_id];
 			dbr_ring_cfg = mod_param->dbr_ring_cfg;
+			if (!dbr_ring_cfg) {
+				direct_buf_rx_info("dbr_ring_cfg is NULL");
+				direct_buf_rx_info("mod id %d mod %s", mod_idx,
+						   g_dbr_module_name[mod_idx].
+						   module_name_str);
+				continue;
+			}
 			srng = dbr_ring_cfg->srng;
 			hal_get_sw_hptp(hal_soc, srng, &tp, &hp);
 			direct_buf_rx_debug("|%11d|%14s|%10x|%10x|",