Input: iqs626a - drop unused device node references

Each call to device/fwnode_get_named_child_node() must be matched
with a call to fwnode_handle_put() once the corresponding node is
no longer in use. This ensures a reference count remains balanced
in the case of dynamic device tree support.

Currently, the driver never calls fwnode_handle_put(); this patch
adds the missing calls. Because fwnode_handle_put() does not take
a const *fwnode_handle, the const qualifier is removed across all
corresponding *fwnode_handle instances.

As part of this change, trackpad channel touch thresholds and ATI
base values are now specified under single trackpad channel child
nodes. This enhancement moves both properties to scalar values as
opposed to arrays, making their types consistent across bindings.

Fixes: f1d2809d ("Input: Add support for Azoteq IQS626A")
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Link: https://lore.kernel.org/r/Y9RQVe/V1Hnw1oly@nixie71


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>