net80211: add driver / crypto methods to set the hardware / software cipher suites

Drivers currently announce hardware crypto cipher support by
setting up ic_cryptocaps.

This adds two public function calls:

• ieee80211_set_software_ciphers() - set the software cipher set;
• ieee80211_set_hardware_ciphers() - set the hardware cipher set.

For now these just call into the newly crypto routines to set the ciphers.

This then adds the two crypto routines, similarly named, to set
the hardware/software cipher suite.

This is a no-op right now - wep/tkip/ccmp are already set by default
so drivers aren't required to call these routines for software
encryption, and drivers already set ic_cryptocaps for hardware
encryption.

Differential Revision: https://reviews.freebsd.org/D44827