LoongArch: BPF: Don't align trampoline size

Currently, arch_alloc_bpf_trampoline() use bpf_prog_pack_alloc() which
will pack multiple trampolines into a huge page. So, no need to assume
the trampoline size is page aligned.

Cc: stable@vger.kernel.org
Tested-by: Vincent Li <vincent.mc.li@gmail.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>