dmaengine: dmatest: fix container_of member in dmatest_callback

dmaengine: dmatest: fix container_of member in dmatest_callback

commit 66b3bd2356e0a1531c71a3dcf96944621e25c17c upstream.

The type of arg passed to dmatest_callback is struct dmatest_done.
It refers to test_done in struct dmatest_thread, not done_wait.

Fixes: 6f6a23a213be ("dmaengine: dmatest: move callback wait ...")
Signed-off-by: Yang Shunyong <shunyong.yang@hxt-semitech.com>
Acked-by: Adam Wallis <awallis@codeaurora.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>