TPM security routines require encryption and decryption with AES in
CFB mode, so add it to the Linux Crypto schemes.  CFB is basically a
one time pad where the pad is generated initially from the encrypted
IV and then subsequently from the encrypted previous block of
ciphertext.  The pad is XOR'd into the plain text to get the final
ciphertext.

https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#CFBSigned-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>