ACPI suspend: build fix for ACPI_SLEEP=n && XEN_SAVE_RESTORE=y.

Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/sleep/main.c

@@ -163,6 +163,8 @@ static void acpi_pm_end(void)
 	acpi_target_sleep_state = ACPI_STATE_S0;
 	acpi_sleep_tts_switch(acpi_target_sleep_state);
 }
+#else /* !CONFIG_ACPI_SLEEP */
+#define acpi_target_sleep_state	ACPI_STATE_S0
 #endif /* CONFIG_ACPI_SLEEP */
 
 #ifdef CONFIG_SUSPEND