otus(4): begin supporting raw transmit parameters in otus_tx()

• Add a comment about the parameters I should support, stolen shamelessly from iwn(4);
• Implement the rate bit for the raw transmit path;
• Print out the host-order versions of each of the transmit bits, so I have a hope in heck of debugging why things are going wrong.

This still doesn't fix 5GHz in the office but that's likely due to a lot
of other configuration parameters being 2GHz-specific. That'll come next.

Tested:

• AR9170 + AR9103 (2/5GHz) 2x2, 5GHz association