crypto: atmel-aes - change atmel_aes_write_ctrl() signature

This patch changes the signature of atmel_aes_write_ctrl() to make it more
generic. This will be used by future patches when implementing new block
cipher modes such as GCM.

Especially atmel_aes_hw_init() is now called outside
atmel_aes_write_ctrl(): this allows to call atmel_aes_write_ctrl() many
times, still initializing the hardware only once.

Indeed, the support of GCM will require to update the Mode Register and
the IV when processing a single request.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>