dt-bindings: input: iqs5xx: Convert to YAML

dt-bindings: input: iqs5xx: Convert to YAML

This patch converts the legacy text-based binding document to YAML
format. Extraneous details and touchscreen properties that weren't
actually supported have been dropped.

The reset GPIO has since been made optional in the driver; this is
now reflected here as well.

Signed-off-by: Jeff LaBundy <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Dmitry Torokhov <[email protected]>