pinctrl: sh-pfc: r8a7796: Add I2C{0,3,5} pins, groups and functions

This patch adds I2C{0,3,5} pins, groups and functions to the R8A7796 SoC.

These pins are physically muxed with other pins. Therefore, setup of
MOD_SEL is needed for exclusive control with other pins.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Ulrich Hecht <uli+renesas@fpond.eu>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>