net/core: make use of the helper macro LIST_HEAD()

list_head can be initialized automatically with LIST_HEAD()
instead of calling INIT_LIST_HEAD(). Here we can simplify
the code.

Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://patch.msgid.link/20240904093243.3345012-6-lihongbo22@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>