audio: waves: check array index

If other caller use audio_hw_send_ma_parameter directly,
that would be a risk if we don’t confirm the index before access it.

Bug: 119283928
Test: build pass / Waves effect - preset / LR swap / LR mix

Change-Id: Ibe2cdb025994a4191ffd85665cf27baddf52fe52
Signed-off-by: Jasmine Cha <chajasmine@google.com>