refactor: Move drivers into properly module.

* Align our driver module layout to properly match Zephyr conventions,
  allowing proper CMake setup to amend the library for each type of driver.

app/module/drivers/sensor/battery/Kconfig

@@ -0,0 +1,28 @@
+# Copyright (c) 2020-2021 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+DT_COMPAT_ZMK_BATTERY_NRF_VDDH := zmk,battery-nrf-vddh
+DT_COMPAT_ZMK_BATTERY_VOLTAGE_DIVIDER := zmk,battery-voltage-divider
+
+config ZMK_BATTERY
+    bool "ZMK battery monitoring"
+    help
+        Enable battery monitoring
+
+config ZMK_BATTERY_NRF_VDDH
+    bool
+    default $(dt_compat_enabled,$(DT_COMPAT_ZMK_BATTERY_NRF_VDDH))
+    select ADC
+    select ZMK_BATTERY
+    depends on SENSOR
+    help
+        Enable ZMK nRF VDDH voltage driver for battery monitoring.
+
+config ZMK_BATTERY_VOLTAGE_DIVIDER
+    bool
+    default $(dt_compat_enabled,$(DT_COMPAT_ZMK_BATTERY_VOLTAGE_DIVIDER))
+    select ADC
+    select ZMK_BATTERY
+    depends on SENSOR
+    help
+        Enable ZMK battery voltage divider driver for battery monitoring.