Make sleep work again when BLE is disabled
In commit 4944aa48 ("fix(ble): Update to changes from new SDK")
a call to BbDrvDisable() was added to sleep_deepsleep(). This
function must, however, only be called when BLE was previously
initialized, otherwise a wakeup from deepsleep will not be possible (if
it ever reaches it?).
Fix this by reworking the BLE enabled check to also be usable here, to
only call BbDrvDisable() when BLE is active.
Fixes: 4944aa48 ("fix(ble): Update to changes from new SDK")
Fixes: #231 (closed)