firmware: stratix10-rsu: replace scnprintf() with sysfs_emit() in *_show() functions

firmware: stratix10-rsu: replace scnprintf() with sysfs_emit() in *_show() functions

Replace scnprintf() with sysfs_emit() in sysfs *_show() functions
in stratix10-rsu.c to follow the kernel's guidelines from
Documentation/filesystems/sysfs.rst.

This improves consistency, safety, and makes the code easier to
maintain and update in the future.

Signed-off-by: Rahul Kumar <rk0006818@gmail.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>