Use index mask when there is no valid input mask from output mask.

When creating PatchRecord, there can be no input channel mask equivalent
to output channel mask. In that case, use index mask instead given there
is already a proper output channel mask.

Bug: 245793724
Test: repo steps in bug
Test: atest audiopolicy_tests AudioPlaybackCaptureTest
Change-Id: Ie6b5d80899a7eeea1fcb88fcdf8cd50bc1a97321