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>