[datapipe] Cache display_state_req_pipe output value. JB#37393

Requested display state can be modified by the filter, thus caching the
original input can lead to subtle errors in case the datapipe value is
queried directly.

Switch to caching filtered output value.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

datapipe.h

@@ -258,7 +258,7 @@ void mce_datapipe_quit(void);
 		display_state_repr(req_target));\
 	execute_datapipe(&display_state_req_pipe,\
 			 GINT_TO_POINTER(req_target),\
-			 USE_INDATA, CACHE_INDATA);\
+			 USE_INDATA, CACHE_OUTDATA);\
     }\
     else {\
 	/* TODO: double check request handling and remove this logging */\