crypto: omap-sham - potential Oops on error in probe

This if statement is reversed so we end up either leaking or Oopsing on
error.

Fixes: dbe24620

 ('crypto: omap-sham - Use dma_request_chan() for requesting DMA channel')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>