Recent Debian (4.4.21-ti-r47): RALINK MT7601 not working

I’ve been using a Mediatek USB wi-fi adapter with a BBB for quite a while. In upgrading to the more-or-less latest Robert Nelson kernel, I can’t get it to work.

It appears that there’s now kernel support for the 7601 chipset - I see a driver module at /lib/modules/4.4.21-ti-r47/kernel/drivers/net/wireless/mediatek/mt7601u/mt7601u.ko.

I’ve also placed the data file from my earlier install at /etc/Wireless/RT2870STA/RT2870STA.dat per discussions here.

The mt7601u module is loading, but I don’t see the expected wlan0 (or ra0) device:

root@vesta:/usr/local/vesta# lsmod | grep 7601
mt7601u 75648 0
mac80211 487050 1 mt7601u
cfg80211 418909 2 mac80211,mt7601u

root@vesta:/usr/local/vesta# iwconfig
lo no wireless extensions.

eth0 no wireless extensions.

usb0 no wireless extensions.

I notice that wpa_supplicant is running with a different driver:
/sbin/wpa_supplicant -s -B -P /run/ -i usb0 -D nl80211,wext -C /run/wpa_supplicant

What am I missing?