refactor(boards): Move QMK Proton-C to HWMv2

Move Proton-C to HWMv2 for use with Zephyr 4.1.

app/boards/arm/proton_c/Kconfig.board

@@ -1,8 +0,0 @@
-# QMK Proton-C board configuration
-
-# Copyright (c) 2020 Pete Johanson
-# SPDX-License-Identifier: MIT
-
-config BOARD_QMK_PROTON_C
-    bool "QMK Proton-C"
-    depends on SOC_STM32F303XC

app/boards/arm/proton_c/Kconfig.defconfig

@@ -1,11 +0,0 @@
-# QMK Proton-C board configuration
-
-# Copyright (c) 2020 Pete Johanson
-# SPDX-License-Identifier: MIT
-
-if BOARD_QMK_PROTON_C
-
-config BOARD
-    default "proton_c"
-
-endif # BOARD_QMK_PROTON_C

app/boards/qmk/proton_c/Kconfig.proton_c

@@ -0,0 +1,5 @@
+# Copyright (c) 2020 Pete Johanson
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_PROTON_C
+    select SOC_STM32F303XC

app/boards/qmk/proton_c/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: proton_c
+  vendor: qmk
+  socs:
+    - name: stm32f303xc

app/boards/qmk/proton_c/proton_c_defconfig

@@ -1,7 +1,5 @@
 # SPDX-License-Identifier: MIT
 
-CONFIG_SOC_SERIES_STM32F3X=y
-CONFIG_SOC_STM32F303XC=y
 # 72MHz system clock
 CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=72000000