bluetooth: reduce BT HCI RX buffer size to fix overflow on snowy

Signed-off-by: Liam McLoughlin <[email protected]>

Author: Hexxeh

third_party/nimble/transport/hci_uart_transport.c

@@ -40,7 +40,7 @@ struct uart_tx {
 
 static TaskHandle_t s_rx_task_handle;
 static CircularBuffer s_rx_buffer;
-static uint8_t s_rx_storage[1024];
+static uint8_t s_rx_storage[256];
 static SemaphoreHandle_t s_rx_data_ready;
 static SemaphoreHandle_t s_cmd_done;