Make printing policy a restriction.

Use existing API instead of creating new method.

Bug: 64140119
Test: cts-tradefed run cts-dev --module CtsDevicePolicyManagerTestCases --test com.android.cts.devicepolicy.MixedDeviceOwnerTest#testPrintingPolicy

Change-Id: I9ff94f4d73824e7bf9aedbb64811ad60fccf9779