pinctrl: freescale: imx7d: support iomux lpsr controller

iMX7D has two iomuxc controllers, iomuxc controller similar as
previous iMX SoC generation and iomuxc-lpsr which provides low
power state rentetion capabilities on gpios that are part of
iomuxc-lpsr

Add iomuxc-lpsr gpio group id's

Signed-off-by: Adrian Alonso <aalonso@freescale.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>