lint: Fix some issues in PRESUBMIT.py found by flake8

Fixed some of the following issues:
- E302 expected 2 blank lines, found 1
- E703 statement ends with a semicolon
- E999 SyntaxError: invalid syntax

Bug: None
Change-Id: Ia4c9a2c81168395331f5d2135a7bba1eafcd3640
Reviewed-on: https://chromium-review.googlesource.com/1155625
Reviewed-by: Dirk Pranke <[email protected]>
Commit-Queue: Wei-Yin Chen (陳威尹) <[email protected]>
Cr-Commit-Position: refs/heads/master@{#579285}
1 file changed