dm: pinctrl: Use right device pointer for configuring pinctrl

commit 719cab6d ("dm: pinctrl: convert pinctrl-single to livetree")
converted pinctrl driver to livetree. In this conversion, the call to
read pinctrl-single,pins/bits property is provided with pinctrl device
pointer instead of pinctrl config pointer. Because of this none of the
pins gets configured. Fix it by passing the right udevice pointer.

Fixes: 719cab6d ("dm: pinctrl: convert pinctrl-single to livetree")
Reported-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>