selftests: drivers/dma-buf: Improve message in selftest summary

Selftest udmabuf for the dma-buf driver is skipped when the device file
(e.g. /dev/udmabuf) for the DMA buffer cannot be opened i.e. no DMA buffer
has been allocated.

This patch adds clarity to the SKIP message.

Signed-off-by: Soumya Negi <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/drivers/dma-buf/udmabuf.c

···
 
 	devfd = open("/dev/udmabuf", O_RDWR);
 	if (devfd < 0) {
-		printf("%s: [skip,no-udmabuf]\n", TEST_PREFIX);
+		printf("%s: [skip,no-udmabuf: Unable to access DMA buffer device file]\n",
+		       TEST_PREFIX);
 		exit(77);
 	}