Reenable EC console 'fanduty' command, for testing.

BUG=chrome-os-partner:10747
TEST=manual

Boot the CPU (the fan is off otherwise). From the EC console run

  faninfo

It should show the fan duty cycle changing to maintain a specific RPM.

Run

  fanduty 50
  faninfo

Now the fan duty cycle should be fixed around 50%.

Change-Id: I13e4b0a7e5b2661769d64bf93342483d0419545d
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/25900
Reviewed-by: Randall Spangler <rspangler@chromium.org>

board/link/board.h

@@ -28,6 +28,9 @@
 /* Enable the fake developer switch.  See crosbug.com/p/8884 */
 #define CONFIG_FAKE_DEV_SWITCH
 
+/* Enable direct fan PWM control. See crosbug.com/p/10747 */
+#define CONFIG_CONSOLE_CMD_FANDUTY
+
 /* Fan PWM channels */
 #define FAN_CH_CPU       0  /* CPU fan */
 #define FAN_CH_KBLIGHT   1  /* Keyboard backlight */

chip/lm4/pwm.c

@@ -213,7 +213,7 @@ DECLARE_CONSOLE_COMMAND(fanset, command_fan_set,
 			NULL);
 
 
-#ifdef CONSOLE_COMMAND_FANDUTY
+#ifdef CONFIG_CONSOLE_CMD_FANDUTY
 /* TODO: this is a temporary command for debugging tach issues */
 static int command_fan_duty(int argc, char **argv)
 {