Fix ovs_lib's issue of parsing flow proto field

When 'proto' other than 'ip' and nw_src/nw_dst are provided at the same
time, the proto parameter will be ignored.

Fixes bug: 1223668

Change-Id: Ie813e66995e2a9310ec4b48c0f7de673db2097f1
Merge "Fix ovs_lib's issue of parsing flow proto field"