service: device-tree node vpd to d-bus hw id data

A daemon for transferring Viable Product Data (VPD) from device-tree
nodes to D-Bus as described in the design doc @
https://gerrit.openbmc.org/c/openbmc/docs/+/66369

and discussed in this Technical Oversight Forum topic @
https://github.com/openbmc/technical-oversight-forum/issues/38

Tested:
Ensure 'model' and/or 'serial-number' nodes are populated in
/proc/device-tree. Can be hardcoded into platform DTS via
linux-kernel recipe if needed.

'''
After OBMC boot, calling
> busctl introspect xyz.openbmc_project.MachineContext /xyz/openbmc_project/MachineContext

produces the following output:

NAME                                          TYPE      SIGNATURE  RESULT/VALUE  FLAGS
...
xyz.openbmc_project.Inventory.Decorator.Asset interface -          -             -
.BuildDate                                    property  s          ""            emits-change writable
.Manufacturer                                 property  s          ""            emits-change writable
.Model                                        property  s          "hpe,dl360"   emits-change writable
.PartNumber                                   property  s          ""            emits-change writable
.SerialNumber                                 property  s          "t5texpl"     emits-change writable
...

Note: Writing to one of these properties will update the property on D-Bus without affecting the
underlying device-tree node. An 'updated' event will be fired, so Entity-Manager probes monitoring
a given property would recognize the new value and key off it.
'''

Change-Id: Id52d1fc3b26010c864c7e64d3dfdf0a2b5de9294
Signed-off-by: Chris Sides <Christopher.Sides@hpe.com>
diff --git a/meson_options.txt b/meson_options.txt
index ad9f7ed..d81ab9c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -2,11 +2,14 @@
     'tests', type: 'feature', description: 'Build tests.',
 )
 option(
-    'fru-device', type: 'boolean', description: 'Build fru-device.',
+    'fru-device', type: 'boolean', description: 'Build fru-device VPD parser.',
 )
 option(
     'fru-device-resizefru', value : false, type: 'boolean', description: 'Allow FruDevice to resize FRU areas.',
 )
 option(
+    'devicetree-vpd', type: 'boolean', description: 'Build device-tree VPD parser'
+)
+option(
     'validate-json', type: 'boolean', value: true, description: 'Run JSON schema validation during the build.',
 )