test/py: efi_secboot: apply autopep8

Python's autopep8 can automatically correct some of warnings from pylint
and rewrite the code in a pretty print format. So just do it.

Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

test/py/tests/test_efi_secboot/test_signed.py

@@ -11,6 +11,7 @@ This test verifies image authentication for signed images.
 import pytest
 from defs import *
 
+
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('efi_secure_boot')
 @pytest.mark.buildconfigspec('cmd_efidebug')