samples/kobject: Use sysfs_emit instead of sprintf

sysfs_emit() is preferred over sprintf() when formatting the value to be
returned to user space in show() functions, because it knows about sysfs
buffer specifics and has sanity checks.

Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Link: https://lore.kernel.org/r/20220303183618.1342358-1-phind.uet@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>