Remove non-zero amplitude validation for waveforms

The validation does not exist in Android R and is causing apps to start
crashing in S.

The validation for the static API createOneShot was maintained, as it
already existed in previous releases.

Fix: 184890231
Test: VibrationEffectTest
Change-Id: I606c943a35ddd68ccacab76f0047b9a276b5cf28