clk: renesas: r8a779g0: Add I2C clocks

Add the module clocks used by the I2C Bus Interfaces on the Renesas
R-Car V4H (R8A779G0) SoC.

Extracted from a larger patch in the BSP by Kazuya Mizuguchi.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/f4b94f37950f6e976b68d0b32c324fb026d8b696.1662714852.git.geert+renesas@glider.be