net-test: all_tests.py - fix a lint warning

Fixes:
  Forcing safe mode "style".
  ************* File all_tests.py
  C6202: 17: Importing a member of a module [g-importing-member]
  http://go/gpylint-faq#g-importing-member

Bug: 153035880
Test: ran uml net_tests against Android Kernel Common 4.19
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I924e58fd5c5c4ce380c9d40d6cabe8766491313e
Merged-In: I924e58fd5c5c4ce380c9d40d6cabe8766491313e