feat(ble): introduce Kconfig option to disable Bluetooth profile advertising

This is useful for dongle mode with only USB output.

app/Kconfig

@@ -210,6 +210,10 @@ config ZMK_BLE_MOUSE_REPORT_QUEUE_SIZE
 config ZMK_BLE_CLEAR_BONDS_ON_START
     bool "Configuration that clears all bond information from the keyboard on startup."
 
+config ZMK_BLE_PROFILE_ADVERTISING
+    bool "Advertise on BLE profiles"
+    default y
+
 # HID GATT notifications sent this way are *not* picked up by Linux, and possibly others.
 config BT_GATT_NOTIFY_MULTIPLE
     default n

app/src/ble.c

@@ -175,6 +175,13 @@ bool zmk_ble_profile_is_connected(uint8_t index) {
     advertising_status = ZMK_ADV_CONN;
 
 int update_advertising(void) {
+#if IS_ENABLED(CONFIG_ZMK_SPLIT_ROLE_CENTRAL)
+#if !IS_ENABLED(CONFIG_ZMK_BLE_PROFILE_ADVERTISING)
+    LOG_INF("skipping advertising since profile advertising is disabled");
+    return 0;
+#endif
+#endif
+
     int err = 0;
     bt_addr_le_t *addr;
     struct bt_conn *conn;