ARM: dts: at91: sama5d27_som1_ek: fix typos

Fix typos that prevent proper using of uart2 and uart4 devices.
Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>

arch/arm/boot/dts/at91-sama5d27_som1_ek.dts

@@ -120,7 +120,7 @@ uart2: serial@f8024000 {
 				pinctrl-names = "default";
 				pinctrl-0 = <&pinctrl_mikrobus2_uart>;
 				atmel,use-dma-rx;
-				atmel-use-dma-tx;
+				atmel,use-dma-tx;
 				status = "okay";
 			};
 
@@ -178,7 +178,7 @@ uart3: serial@fc008000 {
 			uart4: serial@fc00c000 {
 				atmel,use-dma-rx;
 				atmel,use-dma-tx;
-				pinctrl-name = "default";
+				pinctrl-names = "default";
 				pinctrl-0 = <&pinctrl_mikrobus1_uart>;
 				status = "okay";
 			};