refactor(boards): Move Pillbug to HWMv2

Migrate the MechWild PillBug board to HWMv2.

app/boards/arm/pillbug/Kconfig.board

@@ -1,6 +0,0 @@
-# Copyright (c) 2022 The ZMK Contributors
-# SPDX-License-Identifier: MIT
-
-config BOARD_PILLBUG
-    bool "PillBug"
-    depends on SOC_NRF52840_QIAA

app/boards/mechwild/pillbug/Kconfig.defconfig

@@ -3,9 +3,6 @@
 
 if BOARD_PILLBUG
 
-config BOARD
-    default "PillBug"
-
 if USB_DEVICE_STACK
 
 config USB_NRFX

app/boards/mechwild/pillbug/Kconfig.pillbug

@@ -0,0 +1,8 @@
+# Copyright (c) 2022 The ZMK Contributors
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_PILLBUG
+    select SOC_NRF52840_QIAA
+    imply RETAINED_MEM
+    imply RETENTION
+    imply RETENTION_BOOT_MODE

app/boards/mechwild/pillbug/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: pillbug
+  vendor: mechwild
+  socs:
+    - name: nrf52840

app/boards/mechwild/pillbug/pillbug.dts

@@ -7,6 +7,8 @@
 /dts-v1/;
 
 #include <nordic/nrf52840_qiaa.dtsi>
+#include <common/nordic/nrf52840_uf2_boot_mode.dtsi>
+
 #include "pillbug-pinctrl.dtsi"
 #include "blackpill_pins.dtsi"
 

app/boards/mechwild/pillbug/pillbug_defconfig

@@ -1,10 +1,6 @@
 # Copyright (c) 2022 The ZMK Contributors
 # SPDX-License-Identifier: MIT
 
-CONFIG_SOC_SERIES_NRF52X=y
-CONFIG_SOC_NRF52840_QIAA=y
-CONFIG_BOARD_PILLBUG=y
-
 # Enable MPU
 CONFIG_ARM_MPU=y