Kernel: Ensure RTL8139NetworkAdapter uses virtual memory correctly

Author: https://github.com/supercomputer7
Commit: 4479e874da
Pull-request: https://github.com/SerenityOS/serenity/pull/1366
Reviewed-by: https://github.com/awesomekling

Kernel/Net/RTL8139NetworkAdapter.h

@@ -67,11 +67,11 @@ private:
 
     IOAddress m_io_base;
     u8 m_interrupt_line { 0 };
-    u32 m_rx_buffer_addr { 0 };
+    OwnPtr<Region> m_rx_buffer;
     u16 m_rx_buffer_offset { 0 };
-    u32 m_tx_buffer_addr[RTL8139_TX_BUFFER_COUNT];
+    Vector<OwnPtr<Region>> m_tx_buffers;
     u8 m_tx_next_buffer { 0 };
-    u32 m_packet_buffer { 0 };
+    OwnPtr<Region> m_packet_buffer;
     bool m_link_up { false };
 };
 }