use flake8 as pep8 tools
enable check and gate for pep8(voting)
Fix below flake8 issues:
E127 continuation line over-indented for visual indent
E211 whitespace before '('
E222 multiple spaces after operator
E302 expected 2 blank lines, found 1
E501 line too long (101 > 79 characters)
E502 the backslash is redundant between brackets
F401 'platform' imported but unused
W391 blank line at end of file
Change-Id: Idfb953e52c8ee35c2adefdf0e4143a381c7f49e2
Story: 2003426
Task: 24596
Signed-off-by: Sun Austin <austin.sun@intel.com>