Input: iqs62x-keys - 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.

Fixes: ce1cb0ee

 ("input: keyboard: Add support for Azoteq IQS620A/621/622/624/625")
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Link: https://lore.kernel.org/r/YyYbYvlkq5cy55dc@nixie71
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>