livepatch/ppc64: Use module_alloc to alloc func_node

hulk inclusion
category: feature
bugzilla: 51924
CVE: NA

---------------------------

In the prev commit, we implement per func_node livepatch
trampoline. For elf abi v1, the trampoline area is also
malloced and it has no permission to execute. So we use
module_alloc to set trampoline executable.

Signed-off-by: Ye Weihua <yeweihua4@huawei.com>
Reviewed-by: Yang Jihong <yangjihong1@huawei.com>
Reviewed-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>