selftests/bpf: Enable dynptr/test_probe_read_user_str_dynptr

Enable previously disabled dynptr/test_probe_read_user_str_dynptr test,
after the fix it depended on was merged into bpf-next.

Signed-off-by: Mykyta Yatsenko <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Acked-by: Yonghong Song <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/DENYLIST

···
 # TEMPORARY
 # Alphabetical order
-dynptr/test_probe_read_user_str_dynptr # disabled until https://patchwork.kernel.org/project/linux-mm/patch/[e-mail]/ makes it into the bpf-next
 get_stack_raw_tp    # spams with kernel warnings until next bpf -> bpf-next merge
 stacktrace_build_id
 stacktrace_build_id_nmi