Kobo: Fix the upgrade progress bar on sunxi

Merges are extremely broken outside of REAGL/REAGLD on recent kernels,
while things appear to mostly behave with REAGL, so, use that...

(AUTO was a bad call on sunxi anyway)

platform/kobo/koreader.sh

@@ -96,7 +96,15 @@ ko_update_check() {
         # Setup the FBInk daemon
         export FBINK_NAMED_PIPE="/tmp/koreader.fbink"
         rm -f "${FBINK_NAMED_PIPE}"
-        FBINK_PID="$(./fbink --daemon 1 %KOREADER% -q -y -6 -P 0)"
+        # We'll want to use REAGL on sunxi, because AUTO is slow, and fast merges are extremely broken outside of REAGL...
+        eval "$(fbink -e | tr ';' '\n' | grep -e isSunxi | tr '\n' ';')"
+        # shellcheck disable=SC2154
+        if [ "${isSunxi}" = "1" ]; then
+            PBAR_WFM="REAGL"
+        else
+            PBAR_WFM="AUTO"
+        fi
+        FBINK_PID="$(./fbink --daemon 1 %KOREADER% -q -y -6 -P 0 -W ${PBAR_WFM})"
         # NOTE: See frontend/ui/otamanager.lua for a few more details on how we squeeze a percentage out of tar's checkpoint feature
         # NOTE: %B should always be 512 in our case, so let stat do part of the maths for us instead of using %s ;).
         FILESIZE="$(stat -c %b "${NEWUPDATE}")"