device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent_dev()

Add fwnode_is_ancestor_of() helper function to check if a fwnode is an
ancestor of another fwnode.

Add fwnode_get_next_parent_dev() helper function that take as input a
fwnode and finds the closest ancestor fwnode that has a corresponding
struct device and returns that struct device.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-11-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>