crypto: caam - remove double buffering for ahash

Previously double buffering was used for storing previous and next
"less-than-block-size" bytes. Double buffering can be removed by moving
the copy of next "less-than-block-size" bytes after current request is
executed by HW.
Signed-off-by: Andrei Botila <andrei.botila@nxp.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>