drm/radeon: fix bo creation retry path

Retry label was at wrong place in function leading to memory
leak.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>