Error code 51 is given when trying to downgrade a device, so this is
required to fix our broken CTS test and give an accurate error code to
the admin.
Change-Id: I436fb7a605dc47dc5388c78c67d7db08ffcf867a
Fixes: 120896091
Test: atest CtsDevicePolicyManagerTestCases:com.android.cts.devicepolicy.DeviceOwnerTest#testInstallUpdate