PM: EM: Fix yamllint warnings in the EM YNL spec

The energy model YNL spec has the following two warnings
when checking with yamlint:

 3:1    warning missing document start "---"  (document-start)
 107:13 error   wrong indentation: expected 10 but found 12  (indentation)

So let’s fix whose lint warnings.

Fixes: bd26631ccd ("PM: EM: Add em.yaml and autogen files")
Suggested-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Link: https://patch.msgid.link/20260108053212.642478-2-changwoo@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/netlink/specs/em.yaml

@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
-
+#
+# Copyright (c) 2025 Valve Corporation.
+#
+---
 name: em
 
 doc: |
@@ -104,7 +107,7 @@ operations:
       attribute-set: pd-table
       event:
         attributes:
-            - pd-id
+          - pd-id
       mcgrp: event
 
 mcast-groups: