base-files: drop fwtool_pre_upgrade

this feature has never worked, the fw image name was not passed and the -t
parameter was missing in the tool invocation. drop the feature.

Signed-off-by: John Crispin <john@phrozen.org>
(cherry picked from commit 5e1b4c57de)

package/base-files/files/lib/upgrade/fwtool.sh

@@ -1,7 +1,3 @@
-fwtool_pre_upgrade() {
-	fwtool -q -i /dev/null "$1"
-}
-
 fwtool_check_image() {
 	[ $# -gt 1 ] && return 1
 

package/base-files/files/sbin/sysupgrade

@@ -137,7 +137,6 @@ add_overlayfiles() {
 
 # hooks
 sysupgrade_image_check="fwtool_check_image platform_check_image"
-sysupgrade_pre_upgrade="fwtool_pre_upgrade"
 
 if [ $SAVE_OVERLAY = 1 ]; then
 	[ ! -d /overlay/upper/etc ] && {
@@ -264,8 +263,6 @@ else
 	rm -f /tmp/sysupgrade.always.overwrite.bootdisk.partmap
 fi
 
-run_hooks "" $sysupgrade_pre_upgrade
-
 install_bin /sbin/upgraded
 v "Commencing upgrade. Closing all shell sessions."