dt-bindings: pinctrl: pincfg-node: add restrictions on conflicting properties

dt-bindings: pinctrl: pincfg-node: add restrictions on conflicting properties

Many of the possible pincfg properties are not compatible with one
another, either because they represent mutually exclusive states for a
pin or because they provide the same information in different units.

Add some simple restrictions to prevent invalid configurations.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>