ice: Fix possible NULL pointer de-reference

A recent update to smatch is causing it to report the error "we previously
assumed 'm_entry->vsi_list_info' could be null". Fix that.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_switch.c

@@ -1247,6 +1247,9 @@ ice_add_update_vsi_list(struct ice_hw *hw,
 		u16 vsi_handle = new_fltr->vsi_handle;
 		enum ice_adminq_opc opcode;
 
+		if (!m_entry->vsi_list_info)
+			return ICE_ERR_CFG;
+
 		/* A rule already exists with the new VSI being added */
 		if (test_bit(vsi_handle, m_entry->vsi_list_info->vsi_map))
 			return 0;