lava: Drop spurious tool setting

Validating the job definitions when resubmitting them yields:

    Valid definition with warnings:
      extra keys not allowed
      @ data['actions[2]']['deploy']['usb']['tool']

Get rid of the extra setting to make LAVA happier.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

lava/common-boot-tpl.yaml

@@ -86,8 +86,6 @@ actions:
         minutes: 60
       to: usb
       device: {{deploy_device}}
-      tool:
-        prompts: ['copying time: [0-9ms\.\ ]+, copying speed [0-9\.]+ MiB\/sec']
       images:
         image:
           url: {{boot.image_url('gz')}}
@@ -98,7 +96,7 @@ actions:
       writer:
         tool: /usr/bin/bmaptool
         options: copy {DOWNLOAD_URL} {DEVICE}
-        prompt: 'bmaptool: info'
+        prompt: 'bmaptool: info: copying time:'
 
   - boot:
       namespace: system