dt-bindings: i2c: add generic properties for GPIO bus recovery

The I2C GPIO bus recovery properties consist of two GPIOS and one extra
pinctrl state ("gpio" or "recovery"). "recovery" pinctrl state is
considered deprecated and "gpio" should be used instead.
Not all are mandatory for recovery.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Reviewed-by: Rob Herring <robh@kernel.org>
[wsa: kept sorting, minor whitespace change]
Signed-off-by: Wolfram Sang <wsa@kernel.org>