rijndael: clean-up generic bulk functions

* cipher/rijndael.c (_gcry_aes_cfb_enc, _gcry_aes_cbc_enc)
(_gcry_aes_ctr_enc, _gcry_aes_cfb_dec, _gcry_aes_cbc_dec)
(_gcry_aes_ocb_crypt, _gcry_aes_ocb_auth, _gcry_aes_xts_crypt): Remove
calls to hardware accelerated AES bulk functions.

Patch removes accelerated implementation selection from generic
bulk functions. These are no longer used/needed as setkey
returns accelerated bulk functions for all callers and all
callers have been updated to used those bulk functions.

• Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>