sfxge: rename hunt TX methods to ef10 and use for Medford

Rename all except hunt_tx_qdesc_tso_create(), which creates a
fw-assisted TSO v1 descriptor which isn't supported on Medford.

Submitted by: Mark Spender <mspender at solarflare.com>
Reviewed by: gnn
Sponsored by: Solarflare Communications, Inc.
MFC after: 2 days
Differential Revision: https://reviews.freebsd.org/D4870