state: add functionality to export state description
This patch adds the functionality to export the description of the state, but
not the contents of the variables to a DT node. This will be used in a later
patch to "copy" the state description to the kernel device tree during DT
fixup.
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>