drm: nouveau: Replace sprintf() with sysfs_emit()

drm: nouveau: Replace sprintf() with sysfs_emit()

Replace sprintf() calls with sysfs_emit() to follow current kernel
coding standards.

sysfs_emit() is the preferred method for formatting sysfs output as it
provides better bounds checking and is more secure.

Signed-off-by: Madhur Kumar <madhurkumar004@gmail.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/20251205091804.317801-1-madhurkumar004@gmail.com
Fixes: 11b7d895216f ("drm/nouveau/pm: manual pwm fanspeed management for nv40+ boards")
Cc: <stable@vger.kernel.org> # v3.3+