build: Make print statements in scripts python3 compatible.

Signed-off-by: Johannes Krampf <johannes.krampf@googlemail.com>
diff --git a/scripts/readserial.py b/scripts/readserial.py
index d85392e..5b40fdc 100755
--- a/scripts/readserial.py
+++ b/scripts/readserial.py
@@ -156,11 +156,11 @@
         try:
             import serial
         except ImportError:
-            print """
+            print("""
 Unable to find pyserial package ( http://pyserial.sourceforge.net/ ).
 On Linux machines try: yum install pyserial
 Or: apt-get install python-serial
-"""
+""")
             sys.exit(1)
         ser = serial.Serial(serialport, baud, timeout=0)
     else: