crypto: caam - Return a value directly in caam_hash_cra_init()

* Return a value at the end without storing it in an intermediate variable.

* Delete the local variable "ret" which became unnecessary with
  this refactoring.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>