sw64: ebpf: port arch_prepare_bpf_trampoline()

Port the implementation of the arch_prepare_bpf_trampoline function
for SW64, which enabling support for eBPF fentry, fexit, and struct_ops
features.

We have tested these three features individually using the fentry, fexit,
and dummy test cases from the test_progs program under the tools directory.

Signed-off-by: Jinyu Tang <tjytimi@163.com>
Signed-off-by: Yizhou Chen <oneweek233@163.com>
Tested-by: Yizhou Chen <oneweek233@163.com>
Signed-off-by: Gu Yuchen <guyuchen@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>

Author: tjy-zhu