ARM: rmobile: Replace SH I2C with IIC on Porter

Get rid of the SH I2C driver on Porter and enable the IIC driver
instead . The old SH I2C is completely broken on Porter anyway
and the DM/DT capable IIC driver allows access to the PMIC too.
Use the DM/DT capable driver instead.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>