usertools/devbind: conform to PEP8 recommended style

usertools/devbind: conform to PEP8 recommended style

This fixes most of the warnings from the Flake8 style checker.
The ones remaining are long lines (we allow > 79 characters)
and a line break warning.  The line break style changed in later
versions of PEP 8 and the tool is not updated.

https://www.flake8rules.com/rules/W503.html

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Tested-by: Bruce Richardson <bruce.richardson@intel.com>