ARM: dts: imx6q: add vddsoc/pu setpoint info

i.MX6Q needs to update vddarm, vddsoc/pu regulators when cpu freq
is changed, each setpoint has different voltage, so we need to
pass vddarm, vddsoc/pu's freq-voltage info from dts together.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>