Revert "Revert "ALSA: pcm: Use SG-buffer only when direct DMA is available""

This reverts commit 456a7a73 which is
commit 7d50b295 upstream.

It breaks the Android abi.  If it is required in the future, it can
come back in an abi-safe way.

Bug: 161946584
Change-Id: I517a84f35ae5d791dc6ad9bcdbe3296b9e28c2bd
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>