selftests/bpf: Fix the missing tramp_1 to tramp_40 ops in cfi_stubs

The tramp_1 to tramp_40 ops is not set in the cfi_stubs in the
bpf_testmod_ops. It fails the struct_ops_multi_pages test after
retiring the unsupported_ops in the earlier patch.

This patch initializes them in a loop during the bpf_testmod_init().

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240722183049.2254692-3-martin.lau@linux.dev


Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>