Revert "drm/radeon: hold reference to fences in radeon_sa_bo_new"

This reverts commit 8d5e1e5af0c667545c202e8f4051f77aa3bf31b7 which was
commit f6ff4f67cdf8455d0a4226eeeaf5af17c37d05eb upstream.

It breaks working hardware, a backported version might be provided at
some unknown time in the future.

Reported-by: Erik Andersen <andersen@codepoet.org>
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>