Fix bug in sysfs_set_debug() affecting stdin

The close() of the sysfs_notify fd was incorrectly put in the else clause
corresponding to the check for V2 debug. This closes stdin (fd 0) and leads to
scanf in menu.c returning EBADF and a loop because this return value was not
being checked.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Release v1.15