dma: intel_mid_dma: fix double free on mid_setup_dma error path

We should not call kfree(dma) in mid_setup_dma error path because
the memory is allocated in intel_mid_dma_probe and will be freed
in intel_mid_dma_probe error path if mid_setup_dma return error.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>