Remove read check for xt_idletimer dir.

untrusted_app does not need read permission for the xt_idletimer dir,
but rather just needs to make sure the kernel module is present. Remove
the canRead() check as getattr is sufficient for the latter need.

(cherry-picked from commit: ce3a216d2f54ddf56821373ecc9d1d9388e110f5)

Bug: 26792534
Change-Id: Ifccd6712336389ba7cd7424c5304c1056e0e05ef
diff --git a/tests/tests/permission/src/android/permission/cts/FileSystemPermissionTest.java b/tests/tests/permission/src/android/permission/cts/FileSystemPermissionTest.java
index 450d572..dfe3f6e 100644
--- a/tests/tests/permission/src/android/permission/cts/FileSystemPermissionTest.java
+++ b/tests/tests/permission/src/android/permission/cts/FileSystemPermissionTest.java
@@ -276,7 +276,6 @@
     public void testIdletimerDirectoryExistsAndSane() throws Exception {
         File dir = new File("/sys/class/xt_idletimer");
         assertTrue(dir.isDirectory());
-        assertTrue(dir.canRead());
         assertFalse(dir.canWrite());
         assertTrue(dir.canExecute());