Audio HAL: Allow setters to not be implemented

setSampleRate, setChannelMask, setFormat
may not be implemented by the HAL, although this is not documented in
the HAL API.
Currently the VTS test requires their implementation if the respective
getSupported{SampleRate,ChannelMask,Format} are supported.

Relax this requirement as the framework never calls those setters.

Note that the optionality of those functions will be documented
in the next HAL API version.

Test: vts-tradefed run commandAndExit vts --module VtsHalAudioV2_0Target -t CheckConfig.audioPolicyConfigurationValidation
Bug: 69811500
Change-Id: I3a390ae925cabd99e7f1ed4a627e71ad87b1b437
Signed-off-by: Kevin Rocard <krocard@google.com>