carousel: Fix homing bug.

Fix a typo which left the carousel turning after homing completed
in index mode

Signed-off-by: andypugh <andy@bodgesoc.org>

Author: andypugh

src/hal/components/carousel.comp

@@ -302,7 +302,7 @@ FUNCTION(_){
         } else {
             motor_fwd = 0;
             motor_rev = 0;
-            motor_rev = hold_dc;
+            motor_vel = hold_dc;
             active = 0;
             if (enable) ready = 1;
             state = 4;