net/dump: Rework net-dump init functions

net/dump: Rework net-dump init functions

Move the creation of the dump client from net_dump_init() into
net_init_dump(), so we can later use the former function for
dump via netfilter, too. Also rename net_dump_init() to
net_dump_state_init() to make it easier distinguishable from
net_init_dump().

Reviewed-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>