rockchip: spl-boot-order: show DT path for missing device

rockchip: spl-boot-order: show DT path for missing device

When debugging the SPL boot order, the node ID of a device which hasn't
been found is printed but it can be quite hard to relate that to the
specific devicetree node. To aid debugging, print the node path instead of
the cryptic node ID.

Original debug message:

    board_boot_order: could not map node @73c to a boot-device

With this patch applied this becomes e.g:

   board_boot_order: could not map node /spi@ff1d0000/flash@0 to a boot-device

Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>