Add defines for WRITE_UNCORRECTABLE ATA command, and improve command logging

Add #defines for ATA_WRITE_UNCORRECTABLE48 and its features. Update the
decoding in ATACAM to recognize the new values. Also improve command
decoding for a few other commands (SMART, NOP, SET_FEATURES). Bring the
decoding in ata(4) up to parity with ATACAM.

Reviewed by: mav, imp
MFC after: 1 month
Sponsored by: Panasas, Inc.
Differential Revision: https://reviews.freebsd.org/D5181