iwx: migrate to new net80211 encryption key API

[adrian]

Summary

Migrate to the new encryption key API rather than poking at the
key struct directly.

[bz]

sys/dev/iwx/if_iwx.c

11133

const uint8_t *wk_key:
uint16_t wk_keylen;

wk_key = ieee80211_crypto_get_key_data(k);
wk_keylen = ieee80211_crypto_get_key_len(k);

memcpy(cmd.common.key, wk_key, MIN(sizeof(cmd.common.key), wk_keylen));
IWX_DPRINTF(sc, IWX_DEBUG_KEYMGMT, "%s: key: id=%d, len=%i, key=%*D\n",
    __func__, id, wk_keylen, wk_keylen, wk_key, "");

Looks a lot more readable in the long run and fits into 80 char wide lines.

Though it still doesn't ensure that the actual key_data does not change from under you for as long as the key_update_begin/end are dummy functions; the pointer will stay fine.