crypto: picoxcell - Use dev_get_drvdata()

Using dev_get_drvdata directly.

Cc: Jamie Iles <jamie@jamieiles.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>