LoongArch: BPF: Remove duplicated bpf_flush_icache()

The bpf_flush_icache() is called by bpf_arch_text_copy() already. So
remove it. This has been done in arm64 and riscv.

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>

arch/loongarch/net/bpf_jit.c

@@ -1718,7 +1718,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image,
 		goto out;
 	}
 
-	bpf_flush_icache(ro_image, ro_image_end);
 out:
 	kvfree(image);
 	return ret < 0 ? ret : size;