example: add key words to arc_feature examples

the key words are useful for automation to detect if the example
is passed

Signed-off-by: Jingru Wang <jingru@synopsys.com>

Author: wangnuannuan

example/baremetal/arc_feature/cache/main.c

@@ -72,7 +72,7 @@ int main(void)
 				cache_ver, cache_size, cache_ways, cache_llen);
 		build_cfg = _arc_aux_read(AUX_BCR_I_CACHE);
 	} else {
-		EMBARC_PRINTF("no data cache, error!\n");
+		EMBARC_PRINTF("Test Error: no data cache\n");
 		while(1);
 	}
 

example/baremetal/arc_feature/timer_interrupt/main.c

@@ -113,7 +113,7 @@ int main(void)
 		timer_start(TIMER_0, TIMER_CTRL_W, 5*BOARD_CPU_CLOCK);
 	}
 
-	EMBARC_PRINTF("---end----\r\n");
+	EMBARC_PRINTF("Timer Test Done\n");
 	while(1);
 	return E_SYS;
 }

example/baremetal/arc_feature/udma/main.c

@@ -317,7 +317,7 @@ int main( void )
 	dmac_init(&udma);
 	ret = dma_prepare();
 	if (ret == DMA_CHN_INVALID) {
-		EMBARC_PRINTF("dma channel failed, exit.\r\n");
+		EMBARC_PRINTF("Test Error: dma channel failed, exit.\r\n");
 		return -1;
 	}
 	EMBARC_PRINTF("Performance benchmark timer overhead is %u cycles\r\n", perf_overhead());
@@ -369,5 +369,6 @@ int main( void )
 	}
 	dma_finish();
 	dmac_close();
+	EMBARC_PRINTF("uDMA Test Done\n");
 	return 0;
 }