selftests/bpf: enable tracing_struct tests for arm64

Now that the constraint preventing attachment to functions consuming
struct on stack has been removed from the kernel (and moved to pahole,
with a slightly smarter detection, to prevent only those that are
packed), re-enable the tracing_struct tests for arm64.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: Tropicao