crypto/caam: Export gen_split_key symbol for other modules

In 3.6-rc3, without this patch, the following error occurs with a modular build:

ERROR: "gen_split_key" [drivers/crypto/caam/caamhash.ko] undefined!
ERROR: "gen_split_key" [drivers/crypto/caam/caamalg.ko] undefined!

Signed-off-by: Ben Collins <ben.c@servergy.com>
Cc: Yuan Kang <Yuan.Kang@freescale.com>
Acked-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>