Remove deadlock due to PWM being already exported

scripts/SATA-hat.sh

@@ -42,9 +42,10 @@ enable_pwm_channel() {
 }
 
 set_pwm() {
-    enable_pwm_channel 1
     if [ "$1" = "clean" ]; then
         echo 1 >$PWM_PATH/unexport
+    else
+        enable_pwm_channel 1
     fi
 }