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

This reverts commit 140797d0 which is
commit 3ad796cb 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: I598f1eb85eb53626e381c0225b6cbc04bd292294
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>