pinctrl: imx: Push imx_pinctrl_ops into drivers and staticize

Move imx_pinctrl_ops into drivers and staticize. This is preparatory
patch for follow up pinctrl drivers which will not use this variant
of imx_pinctrl_ops content. This should not change size, as most of
the deployments compiled in one pinctrl driver anyway. No functional
change.

Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/drivers/pinctrl/nxp/pinctrl-imx8ulp.c b/drivers/pinctrl/nxp/pinctrl-imx8ulp.c
index 73d3c00..0fb116a 100644
--- a/drivers/pinctrl/nxp/pinctrl-imx8ulp.c
+++ b/drivers/pinctrl/nxp/pinctrl-imx8ulp.c
@@ -31,6 +31,10 @@
 	{ /* sentinel */ }
 };
 
+static const struct pinctrl_ops imx_pinctrl_ops = {
+	.set_state = imx_pinctrl_set_state,
+};
+
 U_BOOT_DRIVER(imx8ulp_pinctrl) = {
 	.name = "imx8ulp-pinctrl",
 	.id = UCLASS_PINCTRL,