ACPICA: Support for custom ACPICA build for ACPI 5 reduced hardware

Add ACPI_REDUCED_HARDWARE flag that removes all hardware-related
code (about 10% code, 5% static data).

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/acpica/hwacpi.c b/drivers/acpi/acpica/hwacpi.c
index d21ec5f..d0b9ed5 100644
--- a/drivers/acpi/acpica/hwacpi.c
+++ b/drivers/acpi/acpica/hwacpi.c
@@ -48,6 +48,7 @@
 #define _COMPONENT          ACPI_HARDWARE
 ACPI_MODULE_NAME("hwacpi")
 
+#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
 /******************************************************************************
  *
  * FUNCTION:    acpi_hw_set_mode
@@ -166,3 +167,5 @@
 		return_UINT32(ACPI_SYS_MODE_LEGACY);
 	}
 }
+
+#endif				/* !ACPI_REDUCED_HARDWARE */