power: reset: reboot-mode: fix -Wformat-security warning

power: reset: reboot-mode: fix -Wformat-security warning

The device_create() function expects a format string to construct a device
name, so passing a variable here introduces a possible vulnerability in
case the string can contain '%' characters:

drivers/power/reset/reboot-mode.c:148:22: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
drivers/power/reset/reboot-mode.c:148:22: note: treat the string as an argument to avoid this
  148 |                                                  (void *)priv, reboot->dev->driver->name);

Use an trivial "%s" format instead and pass the name as the string to be
included here.

Fixes: cfaf0a90789a ("power: reset: reboot-mode: Expose sysfs for registered reboot_modes")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260306150738.497978-1-arnd@kernel.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>