arm64: dts: imx8mp-phyboard-pollux-rdk: correct uart pad settings

BIT3 and BIT0 are reserved bits, should not touch.

Fixes: 846f752866 ("arm64: dts: imx8mp-phyboard-pollux-rdk: Change debug UART")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp-phyboard-pollux-rdk.dts

@@ -156,8 +156,8 @@
 
 	pinctrl_uart1: uart1grp {
 		fsl,pins = <
-			MX8MP_IOMUXC_UART1_RXD__UART1_DCE_RX	0x49
-			MX8MP_IOMUXC_UART1_TXD__UART1_DCE_TX	0x49
+			MX8MP_IOMUXC_UART1_RXD__UART1_DCE_RX	0x40
+			MX8MP_IOMUXC_UART1_TXD__UART1_DCE_TX	0x40
 		>;
 	};