Fixes for AES CTR mode from mikeb:

Fixes for AES CTR mode from mikeb:

o Fix up counter increment for buffers larger then 64 bytes, by
  calling the increment routine before loading the IV into the
  encryption routine input register.

o In aesni_encdec() regenerate the IV for every new request.

Also use nice defines instead of magic constants for the size
of ses_iv.