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

commit 676bc2e1e4f9072f7a640d5b7c99ffdf9709a6e7 upstream.

This reverts commit d1c7871ddb1f588b8eb35affd9ee1a3d5e11cd0c.

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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>