x86: make sysupgrade.tgz reachable again

Moving binding mount before check for saved sysupgrade configuration
made it unreachable. Fix it by moving binding mount after the check.

Fixes: f78b2616 (x86: mount writable bootfs)
Reported-by: Lucian Cristian <luci@powerneth.ro>
Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>

target/linux/x86/base-files/lib/preinit/79_move_config

@@ -9,10 +9,10 @@ move_config() {
 	if export_bootdevice && export_partdevice partdev 1; then
 		mkdir -p /boot
 		mount -t ext4 -o rw,noatime "/dev/$partdev" /boot
-		mount --bind /boot/boot /boot
 		if [ -f /boot/sysupgrade.tgz ]; then
 			mv -f /boot/sysupgrade.tgz /
 		fi
+		mount --bind /boot/boot /boot
 	fi
 }