boards: arm: efr32mg_sltb004a: Convert to v2

Converts the board to hwmv2

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

boards/silabs/efr32mg_sltb004a/Kconfig.defconfig

@@ -5,9 +5,6 @@
 
 if BOARD_EFR32MG_SLTB004A
 
-config BOARD
-	default "efr32mg_sltb004a"
-
 config CMU_HFXO_FREQ
 	default 40000000
 

boards/silabs/efr32mg_sltb004a/Kconfig.efr32mg_sltb004a

@@ -4,6 +4,4 @@
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_EFR32MG_SLTB004A
-	bool "SiLabs EFR32MG-SLTB004A (Thunderboard Sense 2)"
-	depends on SOC_SERIES_EFR32MG12P
 	select SOC_PART_NUMBER_EFR32MG12P332F1024GL125

boards/silabs/efr32mg_sltb004a/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: efr32mg_sltb004a
+  vendor: silabs
+  socs:
+  - name: efr32mg12p332f1024gl125

boards/silabs/efr32mg_sltb004a/efr32mg_sltb004a_defconfig

@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 
 CONFIG_ARM_MPU=y
-CONFIG_SOC_SERIES_EFR32MG12P=y
-CONFIG_BOARD_EFR32MG_SLTB004A=y
 CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y
 CONFIG_SERIAL=y