acpi: Add a function to get a device path and scope

Add a function to build up the ACPI path for a device and another for its
scope.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/lib/acpi/Makefile b/lib/acpi/Makefile
index 660491e..caae6c0 100644
--- a/lib/acpi/Makefile
+++ b/lib/acpi/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0+
 #
 
+obj-y += acpi_device.o
 obj-y += acpi_table.o