Input: i8042 - rework DT node name comparisons

Convert string compares of DT node names to use of_node_name_eq helper
instead. For the root node on SUN DT, we need to retrieve the 'name'
property as it is the rare case where the 'name' property and node name
differ. With both changes, it removes direct access to the node name
pointer.

While at it, convert the open coded loop to use for_each_child_of_node().

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>