This new ubus method provides more properly-formatted details about
firmware file. Use it to check if uploaded image is valid.
The old "sysupgrade --test" method is left for now to provide stderr
output.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
[Added missing ACL, add default value for the ubus failure case]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
7c108683c6