zephyr/boards: Add config for bbc_microbit_v2.

This enables the bluetooth module.  GAP scanning and advertising works.

Signed-off-by: Damien George <damien@micropython.org>

ports/zephyr/boards/bbc_microbit_v2.conf

@@ -0,0 +1,8 @@
+CONFIG_CONSOLE_SUBSYS=n
+CONFIG_NETWORKING=n
+CONFIG_BT=y
+CONFIG_BT_DEVICE_NAME_DYNAMIC=y
+CONFIG_BT_PERIPHERAL=y
+CONFIG_BT_CENTRAL=y
+
+CONFIG_MICROPY_HEAP_SIZE=98304