cros_bundle_firmware: Add --set-node-enable option

Add an option to allow device tree nodes to be enabled or disabled.

--set-node-enable <node> <value>

<node> is either a full path to a node, or an alias which itself points
to a node.
<value> is either 0 (to set status = "ok") or 1 (to set status = "disabled").

BUG=chrome-os-partner:7952
TEST=manual
Using the tegra2-seaboard fdt:
$ cros_bundle_firmware --set-node-enable console 0 -O out
$ fdtdump out/updated.dtb
Manually verify that status = "disabled"; appears in node serial@70006300

$ cros_bundle_firmware --set-node-enable console 1 -O out
$ fdtdump out/updated.dtb
Manually verify that status = "ok"; appears in node serial@70006300

Do the same with:
$ cros_bundle_firmware --set-node-enable console 0 -O out

Try:
$ cros_bundle_firmware --set-node-enable fred 0 -O out
See that we get a warning:
Cannot find alias 'fred' - ignoring

Change-Id: I45442b24c9c26955f0c9dcc6467d20ebb0b34930
Reviewed-on: https://gerrit.chromium.org/gerrit/22283
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Commit-Ready: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2 files changed