boards: efm32gg_sltb009a: uart: Fix USART0 loc 1

Silabs Thunderboard EFM32GG12 (OPN: SLTB009A) connects USART0
location 1 to the VCOM pins of the on-board debugger.

US0_TX loc 1 is pin PE7
US0_RX loc 1 is pin PE6

Signed-off-by: Alex Hogen <alex@edt.com>

Author: edt-alex

boards/silabs/dev_kits/sltb009a/sltb009a-pinctrl.dtsi

@@ -10,10 +10,10 @@
 	/* configuration for usart0 device, default state - operating as UART */
 	usart0_default: usart0_default {
 		group1 {
-			psels = <GECKO_PSEL(UART_TX, E, 0)>,
-				<GECKO_PSEL(UART_RX, E, 1)>,
-				<GECKO_LOC(UART_TX, 7)>,
-				<GECKO_LOC(UART_RX, 6)>;
+			psels = <GECKO_PSEL(UART_TX, E, 7)>,
+				<GECKO_PSEL(UART_RX, E, 6)>,
+				<GECKO_LOC(UART_TX, 1)>,
+				<GECKO_LOC(UART_RX, 1)>;
 		};
 	};