omx: add OMX_EventDataSpaceChanged

This is used internally by IOMX to signal a dataspace change by a surface
encoder.

Bug: 25684127
Change-Id: I42d4ec1db422fa62c251ce197495c6e8ab1430b3
diff --git a/include/media/openmax/OMX_AsString.h b/include/media/openmax/OMX_AsString.h
index aacffad..5fb8ca8 100644
--- a/include/media/openmax/OMX_AsString.h
+++ b/include/media/openmax/OMX_AsString.h
@@ -292,6 +292,7 @@
 //      case OMX_EventDynamicResourcesAvailable: return "DynamicResourcesAvailable";
 //      case OMX_EventPortFormatDetected:        return "PortFormatDetected";
         case OMX_EventOutputRendered:            return "OutputRendered";
+        case OMX_EventDataSpaceChanged:          return "DataSpaceChanged";
         default:                                 return def;
     }
 }