Update doc of setUsage and setContentType in AAudioStreamBuilder.

The usage and content type are only used for output stream. Update the
doc of AAudioStreamBuilder_setUsage/setContentType to indicate this two
APIs must only be used for output stream.

Test: make
Bug: 143772798
Change-Id: I8b500aa1d5b660d19552cbbaec305d3a8c37e39d
1 file changed