dt-bindings: i2c: nvidia,tegra20-i2c: Document Tegra264 I2C

dt-bindings: i2c: nvidia,tegra20-i2c: Document Tegra264 I2C

Tegra264 has 17 generic I2C controllers, two of which are in always-on
partition of the SoC. In addition to the features supported by Tegra194
it also supports a SW mutex register to allow sharing the same I2C
instance across multiple firmware.

Document compatible string "nvidia,tegra264-i2c" for Tegra264 I2C.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>