crypto: atmel-sha - Switch to managed version of kzalloc

This patch switches data allocation from kzalloc to devm_kzalloc.
It also removed some kfree() on data that was earlier allocated
using devm_kzalloc().

CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Grant Likely <grant.likely@linaro.org>
CC: Rob Herring <robh+dt@kernel.org>
CC: Nicolas Ferre <nicolas.ferre@atmel.com>

Signed-off-by: Pramod Gurav <pramod.gurav@smartplayin.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>