qapi: Fix some pycodestyle-3 complaints

qapi: Fix some pycodestyle-3 complaints

Fix the following issues:

    common.py:873:13: E129 visually indented line with same indent as next logical line
    common.py:1766:5: E741 ambiguous variable name 'l'
    common.py:1784:1: E305 expected 2 blank lines after class or function definition, found 1
    common.py:1833:1: E305 expected 2 blank lines after class or function definition, found 1
    common.py:1843:1: E305 expected 2 blank lines after class or function definition, found 1
    visit.py:181:18: E127 continuation line over-indented for visual indent

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20180621083551.775-1-armbru@redhat.com>
[Fixup squashed in:]
Message-ID: <871sd0nzw9.fsf@dusky.pond.sub.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>