test/py: do not import pytest multiple times

Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>

test/py/u_boot_utils.py

@@ -11,7 +11,6 @@ import os.path
 import pytest
 import sys
 import time
-import pytest
 
 def md5sum_data(data):
     """Calculate the MD5 hash of some data.