Fix PR #295 BT MAC overrun

Reduce MAC printing from four characters to two characters

Author: nseidle

Firmware/RTK_Surveyor/Display.ino

@@ -362,7 +362,7 @@ void updateDisplay()
         const uint8_t * rtkMacAddress = getMacAddress();
 
         //Print only last two digits of MAC
-        sprintf(macAddress, "%02X%02X", rtkMacAddress[4], rtkMacAddress[5]);
+        sprintf(macAddress, "%02X", rtkMacAddress[5]);
         oled.setFont(QW_FONT_5X7); //Set font to smallest
         oled.setCursor(0, 3);
         oled.print(macAddress);
@@ -406,7 +406,7 @@ void updateDisplay()
         const uint8_t * rtkMacAddress = getMacAddress();
 
         //Print only last two digits of MAC
-        sprintf(macAddress, "%02X%02X", rtkMacAddress[4], rtkMacAddress[5]);
+        sprintf(macAddress, "%02X", rtkMacAddress[5]);
         oled.setFont(QW_FONT_5X7); //Set font to smallest
         oled.setCursor(14, 3);
         oled.print(macAddress);