This reverts commit e96a9a9af8.
The change breaks sysupgrade through LuCI and two-stage sysupgrade on
NAND targets. There is also a mismatch of file paths in lock and unlock
operations.
This commit was apparently neither properly tested, nor reviewed, so
drop it for now.
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
361c8b4ee4