crypto: omap-sham - clear dma flags only after omap_sham_update_dma_stop()

We should not clear FLAGS_DMA_ACTIVE before omap_sham_update_dma_stop() is
done calling dma_unmap_sg(). We already clear FLAGS_DMA_ACTIVE at the
end of omap_sham_update_dma_stop().

The early clearing of FLAGS_DMA_ACTIVE is not causing issues as we do not
need to defer anything based on FLAGS_DMA_ACTIVE currently. So this can be
applied as clean-up.

Cc: Lokesh Vutla <lokeshvutla@ti.com>
Cc: Tero Kristo <kristo@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>