modules: update OpenWrt

a8c92e9eda opkg: Fix PKG_MIRROR_HASH
844b892a74 ath10k-firmware: fix mirror hash
7e9d84ee4a opkg: update to latest Git HEAD
81f3f6540e wireguard: bump to 1.0.20200506
b956f6bd13 wireguard: bump to 20191226
c61fbdd087 odhcpd: fix PKG_SOURCE_DATE
5e8b50da15 odhcpd: fix lan host reachibility due to identical RIO and PIO prefixes (FS#3056)
ac5d5d8d09 ustream-ssl: update to 19.07 Git HEAD
a6caa8fad1 uhttpd: update to 19.07 Git HEAD
3b9e4d6d4c fstools: update to the latest version