selftests/bpf: Remove test_align leftovers

Calling generic selftests "make install" fails as rsync expects all
files from TEST_GEN_PROGS to be present. The binary is not generated
anymore (commit 3b09d27c) so we can safely remove it from there
and also from gitignore.

Fixes: 3b09d27c

 ("selftests/bpf: Move test_align under test_progs")
Signed-off-by: Veronika Kabatova <vkabatov@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20200819160710.1345956-1-vkabatov@redhat.com