yaml: update default led.yaml config

The default led.yaml configuration having old definition for a led
priority.
Running `scripts/parse_led.py` goes failure:
```bash
ValueError: Invalid Configuration for LED [heartbeat] in Group
[bmc_booted]: no group priority or led priority defined
```

The change adds `Priority: "On"` for each Leds across all led groups.

Tested:
* run `scripts/parse_led.py -i . -o .`
* the `parse_led.py` generates `led-gen.hpp` properly

Change-Id: Icabb4bc6127a468102387e576e8ce9a54ea07693
Signed-off-by: Igor Kononenko <i.kononenko.e@gmail.com>
diff --git a/led.yaml b/led.yaml
index accbf5e..6c6cc90 100755
--- a/led.yaml
+++ b/led.yaml
@@ -1,6 +1,7 @@
 bmc_booted:
     heartbeat:
         Action: "On"
+        Priority: "On"
 power_on:
     power:
         Action: "On"
@@ -8,34 +9,44 @@
 enclosure_fault:
     front_fault:
         Action: "On"
+        Priority: "On"
     rear_fault:
         Action: "On"
+        Priority: "On"
 enclosure_identify:
     front_id:
         Action: "Blink"
         DutyOn: 50
         Period: 1000
+        Priority: "On"
     rear_id:
         Action: "Blink"
         DutyOn: 50
         Period: 1000
+        Priority: "On"
 fan_fault:
     front_fault:
         Action: "On"
+        Priority: "On"
     fan0:
         Action: "On"
+        Priority: "On"
     rear_fault:
         Action: "On"
+        Priority: "On"
 fan_identify:
     front_id:
         Action: "Blink"
         DutyOn: 50
         Period: 1000
+        Priority: "On"
     rear_id:
         Action: "Blink"
         DutyOn: 50
         Period: 1000
+        Priority: "On"
     fan0:
         Action: "Blink"
         DutyOn: 50
         Period: 1000
+        Priority: "On"