Support float data on aaudio legacy record fast path.

Previously, the format is changed to PCM 16 bit when pcm float is
requested on low latency fast capture mode. The reason is that
AudioRecord doesn't support float data on fast path. Currently,
AudioRecord supports float data on fast mode by adding format conversion
at client side. In that case, in aaudio legacy path, there is no need to
add such a limitation when capturing pcm float.

Bug: 224845829
Test: use oboetester to capture on legacy mode and check AF dump
Change-Id: I5e767467f2b444e153d88638fc6005416f53bf03