qcacld-3.0: Check for NULL before accessing dp_ctx or DP soc.

Check for NULL before accessing dp_ctx or DP SOC in
__dp_bus_bw_compute_timer_stop().

Change-Id: I0d2862c4688f83c3d5f561baaa6ce62e96cca9c3
CRs-Fixed: 3659080
(cherry picked from commit 836a18a866a994edf2ac28adb94356a062b80f3c)

components/dp/core/src/wlan_dp_bus_bandwidth.c

@@ -2177,6 +2177,9 @@ static void __dp_bus_bw_compute_timer_stop(struct wlan_objmgr_psoc *psoc)
 	if (QDF_GLOBAL_FTM_MODE == cds_get_conparam())
 		return;
 
+	if (!dp_ctx || !soc)
+		return;
+
 	ctx = dp_ctx->dp_ops.callback_ctx;
 	is_any_adapter_conn = dp_ctx->dp_ops.dp_any_adapter_connected(ctx);