net-test: set sufficient MEMLOCK rlimit for bpf test

Some devices doesn't set the default memlock memory size,
it's possible to fail the bpf map creation.

Bug: 175087066
Bug: 182760543
Test: via treehugger
Change-Id: I4be25f45aeab044ad6aceda10aa62c61be771ef7
Merged-In: I4be25f45aeab044ad6aceda10aa62c61be771ef7