ARM: shmobile: r8a73a4 dtsi: Add SoC-specific IIC compatible properties

ARM: shmobile: r8a73a4 dtsi: Add SoC-specific IIC compatible properties

The IIC nodes used the generic compatible properties only.
This may cause the driver to fail when using Standard Speed on IIC
masters where the operational clock is driven by the 130 MHz HP clock.

Add the SoC-specific compatible property to fix this.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
(cherry picked from commit 7e9ad4d09d31ac696aa9baf4ff5c06cc015f7528)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>