selftests/bpf: Allow prog name matching for tests with __description

selftests/bpf: Allow prog name matching for tests with __description

For tests that carry a __description tag, allow matching on both the
description string and program name for convenience. Before this commit,
the description string must be spelt out to filter the tests.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260407145606.3991770-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>