ARM: dts: r8a7743: Remove generic compatible string from iic3

The iic3 block on RZ/G1M does not support automatic transmission, unlike
other R-Car SoC's. So dropping the compatibility with the generic version.

Fixes: f523405f ("ARM: dts: r8a7743: Add IIC cores to dtsi")
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>