Revert "drm/radeon: fix bo creation retry path"

This reverts commit d1c7871d.

ttm_bo_init() destroys the BO on failure. So this patch makes
the retry path work with freed memory.  This ends up causing
kernel panics when this path is hit.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org