crypto: atmel - remove empty functions

Pointer members of an object with static storage duration, if not
explicitly initialized, will be initialized to a NULL pointer.
The crypto API checks if these pointers are not NULL before using them,
therefore we can safely remove these empty functions.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>