Various optimizations to software AES-CCM and AES-GCM.

Various optimizations to software AES-CCM and AES-GCM.

- Make use of cursors to avoid data copies for AES-CCM and AES-GCM.

  Pass pointers into the request's input and/or output buffers
  directly to the Update, encrypt, and decrypt hooks rather than
  always copying all data into a temporary block buffer on the stack.

- Move handling for partial final blocks out of the main loop.

  This removes branches from the main loop and permits using
  encrypt/decrypt_last which avoids a memset to clear the rest of the
  block on the stack.

- Shrink the on-stack buffers to assume AES block sizes and CCM/GCM
  tag lengths.

- For AAD data, pass larger chunks to axf->Update.  CCM can take each
  AAD segment in a single call.  GMAC can take multiple blocks at a
  time.

Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D25058