Avoid duplicate source routing rules in Linux
Avoid duplicate source routing rules in Linux

Summary:
Linux doesn't handle `NLM_F_REPLACE` while adding source routing rules. Whenever
the interface status is flapped we add interface addresses and source routing
rules earlier. Which leads to piling up of source routing rules.

In this diff I am just programming intf-address on bringing up the interface and
not programming source routing rules.

Reviewed By: tfangit

Differential Revision: D3881368

fbshipit-source-id: d59176d1f087894bc469a4e01a96936ca5e69d27

peterlei/fboss,peterlei/fboss,peterlei/fboss,peterlei/fboss