audioflinger: Honor config flags when opening s/w patch output

If the patch sink configuration specifies sampling rate, format,
and channel mask, use them when opening the output side of
a software patch.

Bug: 63901775
Test: MSD prototype; Telecom calls via USB headset on Pixel.
Change-Id: I705d46524cfcc59c88c57b18a45bee0c6b922b62