audio policy: fix a2dp output detection

The logic in IOProfile::devicesSupportEncodedFormats()
was only checking if the first device in the list of supported devices
was supporting currently selected A2DP encoding format.
But if more than one devices match the queried types, we need to check
all devices in case one of them supports the selected encoding format.

Bug: 147789166
Test: repro steps in the bug.
Change-Id: I704c5c6278eed524f15e7b73cec68a24f04d3a8c