platform/x86: asus-wmi: fix build without CONFIG_SUSPEND

platform/x86: asus-wmi: fix build without CONFIG_SUSPEND

The patch "Refactor Ally suspend/resume" introduced an
acpi_s2idle_dev_ops for use with ROG Ally which caused a build error
if CONFIG_SUSPEND was not defined.

Signed-off-by: Luke Jones <luke@ljones.dev>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202505090418.DaeaXe4i-lkp@intel.com/
Fixes: feea7bd6b02d ("platform/x86: asus-wmi: Refactor Ally suspend/resume")
Link: https://lore.kernel.org/r/20250524101343.57883-2-luke@ljones.dev
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>