boards: arm: efm32gg_sltb009a: Convert to v2

Converts the board to hwmv2

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

boards/silabs/efm32gg_sltb009a/Kconfig.defconfig

@@ -4,10 +4,6 @@
 
 if BOARD_EFM32GG_SLTB009A
 
-config BOARD
-	string
-	default "efm32gg_sltb009a"
-
 config CMU_HFXO_FREQ
 	default 50000000
 

boards/silabs/efm32gg_sltb009a/Kconfig.efm32gg_sltb009a

@@ -3,6 +3,4 @@
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_EFM32GG_SLTB009A
-	bool "SiLabs EFM32GG-SLTB009A (Giant Gecko 12)"
-	depends on SOC_SERIES_EFM32GG12B
 	select SOC_PART_NUMBER_EFM32GG12B810F1024GM64

boards/silabs/efm32gg_sltb009a/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: efm32gg_sltb009a
+  vendor: silabs
+  socs:
+  - name: efm32gg12b810f1024gm64

boards/silabs/efm32gg_sltb009a/efm32gg_sltb009a_defconfig

@@ -1,8 +1,6 @@
 # Copyright (c) 2023 Antmicro <www.antmicro.com>
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_SOC_SERIES_EFM32GG12B=y
-CONFIG_BOARD_EFM32GG_SLTB009A=y
 CONFIG_ARM_MPU=y
 CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y