crypto: caam - merge identical ahash_final/finup shared desc

Shared descriptors used by ahash_final() and ahash_finup()
are identical, thus get rid of one of them (sh_desc_finup).

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>