Added missing endif for ifdef __AVR_ATmega32U4__ and removed the unnecessary one at the end of the file

quantum/config_common.h

@@ -76,6 +76,7 @@
         } while(0)
 #   else
 #       error "USART configuration is needed."
+#   endif
 #endif
 
 // I'm fairly sure these aren't needed, but oh well - Jack
@@ -125,4 +126,3 @@
 
 #endif
 
-#endif