LoongArch: BPF: Open code and remove invoke_bpf_mod_ret()

LoongArch: BPF: Open code and remove invoke_bpf_mod_ret()

invoke_bpf_mod_ret() is a small wrapper over invoke_bpf_prog(), it
should check the return value of invoke_bpf_prog() and then return
immediately if invoke_bpf_prog() failed, just open code and remove
it due to it is called only once.

Acked-by: Hengqi Chen <hengqi.chen@gmail.com>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>