ar71xx: fix syntax error in /lib/ar71xx.sh

patches/openwrt/0013-fix-UBNT-XM-model-detection.patch

...EL-ending-with-a-space-on-some-TP-LINK-like-devices.patch

...devices-in-AR71XX_MODEL-to-match-labels-image-names.patch

...t/0038-ar71xx-Support-for-Ubiquiti-UniFi-AP-AC-LITE.patch

.../openwrt/0040-ar71xx-Rename-unifiac-to-unifiac-lite.patch

...041-ar71xx-Add-support-for-Ubiquiti-UniFi-AP-AC-PRO.patch

patches/openwrt/0047-ar71xx-add-GL-AR150-support.patch

...0058-ar71xx-add-support-for-TP-LINK-TL-WR842N-ND-v3.patch

...1xx-add-revision-detection-for-D-Link-DIR-505-A1-A2.patch

...510-split-profile-into-2-profiles-cpe210-and-cpe510.patch

.../openwrt/0068-ar71xx-Added-support-for-TL-WA801NDv3.patch