crypto: atmel-{aes,sha,tdes} - Retire crypto_platform_data

These drivers no longer need it as they are only probed via DT.
crypto_platform_data was allocated but unused, so remove it.
This is a follow up for:
commit 45a536e3 ("crypto: atmel-tdes - Retire dma_request_slave_channel_compat()")
commit db28512f ("crypto: atmel-sha - Retire dma_request_slave_channel_compat()")
commit 62f72cbd ("crypto: atmel-aes - Retire dma_request_slave_channel_compat()")

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