radeonsi: Disable asynchronous DMA except for PIPE_BUFFER

radeonsi: Disable asynchronous DMA except for PIPE_BUFFER

Using the asynchronous DMA engine for multi-dimensional operations seems
to cause random GPU lockups for various people. While the root cause for
this might need to be fixed in the kernel, let's disable it for now.

Before re-enabling this, please make sure you can hit all newly enabled
paths in your testing, preferably with both piglit and real world apps,
and get in touch with people on the bug reports below for stability
testing.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85647
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83500
Cc: "10.3 10.4" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Grigori Goronzy <greg@chown.ath.cx>