Change android.permission.RESTRICTED_VR_ACCESS to SystemAPI

android.permission.RESTRICTED_VR_ACCESS is currently an open API. But
since it can only be used by System Apps because of it's protection
level which is "signature|preinstalled". Change this to a @SystemApi.

Bug: 37724255
Test: run gts --module GtsPermissionTestCases
1. Run with two apps having android.permission.RESTRICTED_VR_ACCESS
   before change -- fails.
2. Run with two appshaving android.permission.RESTRICTED_VR_ACCESS
   after this change -- passes.

Change-Id: I9e640b0794fa16d03ba22e8aa75175e7e08dd88b
Signed-off-by: Karthik Ravi Shankar <karthikrs@google.com>
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 5b4a454..4b39646 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -3353,6 +3353,8 @@
         android:protectionLevel="signature" />
 
     <!-- Must be required by system apps when accessing restricted VR APIs.
+         @hide
+         @SystemApi
          <p>Protection level: signature -->
     <permission android:name="android.permission.RESTRICTED_VR_ACCESS"
         android:protectionLevel="signature|preinstalled" />