Typo fix

platformio/builder/scripts/nordicnrf51.py

@@ -33,7 +33,7 @@ if env.subst("$BOARD") == "rfduino":
     env.Replace(
         UPLOADER=join("$PIOPACKAGES_DIR", "tool-rfdloader", "rfdloader"),
         UPLOADERFLAGS=["-q", "$UPLOAD_PORT", "$SOURCES"],
-        UPLOADCMD='"$UPLOADER" $UPLOADERFLAGS"'
+        UPLOADCMD='"$UPLOADER" $UPLOADERFLAGS'
     )
 
 #