crypto: ccree - use devm_k[mz]alloc() for AEAD data

As the lifetime of the AEAD data matches the lifetime of the driver,
AEAD data can be allocated using the managed allocators.
While at it, simplify cc_aead_free() by removing an unneeded cast, and
an unneeded check (aead_handle is always valid here).

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>