ACPI / PM: Fix build for unusual combination of Kconfig options

CONFIG_PM_SLEEP may be set even if CONFIG_ACPI_SLEEP is unset,
although that is unusual.  For this reason, make the headers of
functions built for both CONFIG_ACPI and CONFIG_PM_SLEEP set
simultaneously depend on that combination of Kconfig options
instead of CONFIG_ACPI_SLEEP.

This fixes a build problem reported by Randy Dunlap.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/acpi.h

@@ -511,7 +511,7 @@ static inline int acpi_subsys_runtime_suspend(struct device *dev) { return 0; }
 static inline int acpi_subsys_runtime_resume(struct device *dev) { return 0; }
 #endif
 
-#ifdef CONFIG_ACPI_SLEEP
+#if defined(CONFIG_ACPI) && defined(CONFIG_PM_SLEEP)
 int acpi_dev_suspend_late(struct device *dev);
 int acpi_dev_resume_early(struct device *dev);
 int acpi_subsys_prepare(struct device *dev);