tests/pc8: fix function return value

Looks like I forgot to push this chunk... The test was passing in
cases where you only have eDP monitors due to the fact that we
consider i2c won't work on eDP monitors.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

tests/pc8.c

@@ -578,7 +578,7 @@ static int count_i2c_valid_edids(void)
 
 	closedir(dir);
 
-	return 0;
+	return ret;
 }
 
 /* We run this test when all outputs are turned off. When eDP panels are turned