i2c: rcar: add support for r8a7795 (R-Car H3)

Enable the I2C core for this SoC. I add a new type because this version
has new features (e.g. DMA) which will be added somewhen later.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>