crypto: sahara - Use dmam_alloc_coherent

This patch moves the data allocated using dma_alloc_coherent to the
corresponding managed interface. To be compatible with the change,
various gotos are replaced with direct returns and unneeded labels
are dropped.

Signed-off-by: Vaishali Thakkar <vthakkar1994@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>