ACPI: fan: Replace sprintf()/scnprintf() with sysfs_emit() in show() functions

ACPI: fan: Replace sprintf()/scnprintf() with sysfs_emit() in show() functions

Update two sysfs show() functions in the ACPI fan driver to use sysfs_emit()
and sysfs_emit_at() instead of sprintf() and scnprintf().

 - show_fan_speed(): replaced sprintf() with sysfs_emit().
 - show_state(): replaced scnprintf() with sysfs_emit() for the first
   write, and retained sysfs_emit_at() for incremental writes.

This change is in accordance with Documentation/filesystems/sysfs.rst,
which recommends using sysfs_emit/sysfs_emit_at in all sysfs show()
callbacks for buffer safety, clarity, and consistency.

Signed-off-by: Abdelrahman Fekry <abdelrahmanfekry375@gmail.com>
Link: https://patch.msgid.link/20250621055200.166361-1-abdelrahmanfekry375@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>