Add a driver for the SafeXcel EIP-97.

The EIP-97 is a packet processing module found on the ESPRESSObin. This
commit adds a crypto(9) driver for the crypto and hash engine in this
device. An initial skeleton driver that could attach and submit
requests was written by loos and others at Netgate, and the driver was
finished by me.

Support for separate AAD and output buffers will be added in a separate
commit, to simplify merging to stable/12 (where those features don't
exist).

Reviewed by: gnn, jhb
Feedback from: andrew, cem, manu
MFC after: 1 week
Sponsored by: Rubicon Communications, LLC (Netgate)
Differential Revision: https://reviews.freebsd.org/D25417