Kernel: Add list-compatible constructor for MACAddress

Author: https://github.com/deoxxa
Commit: eb01735ec5
Pull-request: https://github.com/SerenityOS/serenity/pull/499
Reviewed-by: https://github.com/awesomekling

Kernel/Net/MACAddress.h

@@ -13,6 +13,15 @@ public:
     {
         memcpy(m_data, data, 6);
     }
+    MACAddress(u8 a, u8 b, u8 c, u8 d, u8 e, u8 f)
+    {
+        m_data[0] = a;
+        m_data[1] = b;
+        m_data[2] = c;
+        m_data[3] = d;
+        m_data[4] = e;
+        m_data[5] = f;
+    }
     ~MACAddress() {}
 
     u8 operator[](int i) const