imx: imx8mn_evk: enable pinctrl_wdog in SPL

Mark pinctrl_wdog as u-boot,dm-spl to clean up board code,

The set_wdog_reset() function is not necessary as this is handled by
the imx_watchdog.c driver due to the 'fsl,ext-reset-output' property
being set.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi b/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
index 6f70722..4d0ecb0 100644
--- a/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
+++ b/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
@@ -80,6 +80,10 @@
 	u-boot,dm-spl;
 };
 
+&pinctrl_wdog {
+	u-boot,dm-spl;
+};
+
 &gpio1 {
 	u-boot,dm-spl;
 };
diff --git a/board/freescale/imx8mn_evk/spl.c b/board/freescale/imx8mn_evk/spl.c
index 63f335b..3d9aa56 100644
--- a/board/freescale/imx8mn_evk/spl.c
+++ b/board/freescale/imx8mn_evk/spl.c
@@ -115,23 +115,6 @@
 }
 #endif
 
-#define WDOG_PAD_CTRL	(PAD_CTL_DSE6 | PAD_CTL_ODE | PAD_CTL_PUE | PAD_CTL_PE)
-
-static iomux_v3_cfg_t const wdog_pads[] = {
-	IMX8MN_PAD_GPIO1_IO02__WDOG1_WDOG_B  | MUX_PAD_CTRL(WDOG_PAD_CTRL),
-};
-
-int board_early_init_f(void)
-{
-	struct wdog_regs *wdog = (struct wdog_regs *)WDOG1_BASE_ADDR;
-
-	imx_iomux_v3_setup_multiple_pads(wdog_pads, ARRAY_SIZE(wdog_pads));
-
-	set_wdog_reset(wdog);
-
-	return 0;
-}
-
 void board_init_f(ulong dummy)
 {
 	int ret;
@@ -140,8 +123,6 @@
 
 	init_uart_clk(1);
 
-	board_early_init_f();
-
 	timer_init();
 
 	/* Clear the BSS. */