pinctrl: imx-iomux-v3: only register pinctrl when device node is available ...

The pinctrl support is devicetree only, so only register it
when we actually have a devicetree. Otherwise we crash boards
using the iomux-v3 from platform code in pinctrl_register().

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

pinctrl: switch i.MX iomux-v3 support to pinctrl ...

This switches the iomux-v3 (found on i.MX25,35,51,53,6) to pinctrl
support. The old SoC specific API is kept for compatibility. The
pinctrl devicetree support is enabled automatically when OFDEVICE
support is available.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>