cpufreq: speedstep-lib: mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/speedstep-lib.c

@@ -367,7 +367,7 @@ unsigned int speedstep_detect_processor(void)
 			} else
 				return SPEEDSTEP_CPU_PIII_C;
 		}
-
+		/* fall through */
 	default:
 		return 0;
 	}