aes-vaes-avx2: improve case when only CTR needs carry handling
* cipher/rijndael-vaes-avx2-amd64.S (_gcry_vaes_avx2_ctr_enc_amd64): Add handling for the case when only main counter needs carry handling but generated vector counters do not.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>