crypto: atmel-aes - Reset the controller before each use

When using the rfc4543(gcm(aes))) mode, the registers of the hardware
engine are not empty after use. If the engine is not reset before its
next use, the following results will be invalid.

Always reset the hardware engine.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>