boards: arm: efm32gg_stk3701a: Convert to v2

Converts the board to hwmv2

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

boards/silabs/efm32gg_stk3701a/Kconfig.defconfig

@@ -5,10 +5,6 @@
 
 if BOARD_EFM32GG_STK3701A
 
-config BOARD
-	string
-	default "efm32gg_stk3701a"
-
 config CMU_HFXO_FREQ
 	default 50000000
 

boards/silabs/efm32gg_stk3701a/Kconfig.efm32gg_stk3701a

@@ -4,6 +4,4 @@
 # SPDX-License-Identifier: Apache-2.0
 
 config BOARD_EFM32GG_STK3701A
-	bool "SiLabs EFM32GG-STK3701A (Giant Gecko 11)"
-	depends on SOC_SERIES_EFM32GG11B
 	select SOC_PART_NUMBER_EFM32GG11B820F2048GL192

boards/silabs/efm32gg_stk3701a/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: efm32gg_stk3701a
+  vendor: silabs
+  socs:
+  - name: efm32gg11b820f2048gl192

boards/silabs/efm32gg_stk3701a/efm32gg_stk3701a_defconfig

@@ -2,8 +2,6 @@
 # Copyright (c) 2019 Oane Kingma
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_SOC_SERIES_EFM32GG11B=y
-CONFIG_BOARD_EFM32GG_STK3701A=y
 CONFIG_ARM_MPU=y
 CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y