crypto: caam - clean-up in caam_init_rng()

Clean up the code, as indicated by Coccinelle.

Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>