Initialize dmac array to nulls

I don't fully understand why, but I've seen segfaults when the dmac value isn't initialized to 0s.

src/platform/portduino/PortduinoGlue.cpp

@@ -203,7 +203,7 @@ void portduinoSetup()
         }
     }
 
-    uint8_t dmac[6];
+    uint8_t dmac[6] = {0};
     getMacAddr(dmac);
     if (dmac[0] == 0 && dmac[1] == 0 && dmac[2] == 0 && dmac[3] == 0 && dmac[4] == 0 && dmac[5] == 0) {
         std::cout << "*** Blank MAC Address not allowed!" << std::endl;
@@ -531,4 +531,4 @@ bool MAC_from_string(std::string mac_str, uint8_t *dmac)
     } else {
         return false;
     }
-}
+}