ARM: shmobile: r8a7790: Fix I2C controller names

This fixes the issue introduced by the following commit:
b448c904 "ARM: shmobile: r8a7790: add I2C support"

The R8A7790 is an R-Car Gen2 SoC. The clock division factor
(CDF) width is 3 bits on Gen2 as opposed to 2 bits on Gen1.
Fix the device names for R8A7790 SoC to make the R-Car I2C
driver configure the hardware properly.

Changes in V2:
* rebased on top of the latest branch;
* capitalized ARM in the subject line;
* noted the commit that caused the issue in the log.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>