of: kobj: make of_node_is_(initialized|attached) parameters const

of_node_is_initialized() and of_node_is_attached() don't modify the node
objects passed to them, so those parameters should be const.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Link: https://lore.kernel.org/r/20211014173023.2117799-1-nathanl@linux.ibm.com


Signed-off-by: Rob Herring <robh@kernel.org>