modules: update OpenWrt

6e16dd1234 mt76: update to the latest version
76037756d0 kernel: bump 4.14 to 4.14.94
455bfd1065 kernel: bump 4.9 to 4.9.151
fafd7691e6 opkg: update to latest Git head
e789bd2243 opkg: drop argument from check_signature in opkg.conf
3603c2321d ramips: mt7621: fix 5GHz WiFi LED on ZBT WG3526
7f98cd8d50 odhcpd: fix onlink IA check (FS#2060)
abd0f7995e kmod-sched-cake: bump to latest cake

Compile-tested: ar71xx-{tiny,generic}, ramips-mt7621, x86-64