crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error)

Talitos Security Engine AESU considers any input
data size that is not a multiple of 16 bytes to be an error.
This is not a problem in general, except for Counter mode
that is a stream cipher and can have an input of any size.

Test Manager for ctr(aes) fails on 4th test vector which has
a length of 499 while all previous vectors which have a 16 bytes
multiple length succeed.

As suggested by Freescale, round up the input data length to the
nearest 16 bytes.

Fixes: 5e75ae1b ("crypto: talitos - add new crypto modes")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>