selftests/bpf: Pull up printing the test name into test runner

Again, prepare for switching reuseport tests to test_progs framework.
test_progs framework will print the subtest name for us if we set it.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191212102259.418536-9-jakub@cloudflare.com