Thermal cpu cooling: return error if no valid cpu frequency entry

Signed-off-by: Zhang Rui <[e-mail]>

drivers/thermal/cpu_cooling.c

···
 		freq = table[i].frequency;
 		max_level++;
 	}
+
+	/* No valid cpu frequency entry */
+	if (max_level == 0)
+		return -EINVAL;
+
 	/* max_level is an index, not a counter */
 	max_level--;