ARM: rmobile: Fix broken reset code on Porter

The 'reset' command did not work on Porter because the reset code
was accessing the wrong PMIC address over broken I2C bus driver.
Replace the code with DM-aware code and fix up the PMIC address.
This makes the 'reset' command work again.

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