Fixed User HAL dump.

It was not validating the input before storing the response form lshal, which
would crash it later.

Test: adb shell lshal debug android.hardware.automotive.vehicle@2.0::IVehicle/default --set 299896583 a 2
Bug: 146207078

Change-Id: I49a38041e2881224c61e3c645db7c9103d024040