ipv4: Set ifa->ifa_dev in inet_alloc_ifa().

When a new IPv4 address is assigned via ioctl(SIOCSIFADDR),
inet_set_ifa() sets ifa->ifa_dev if it's different from in_dev
passed as an argument.

In this case, ifa is always a newly allocated object, and
ifa->ifa_dev is NULL.

inet_set_ifa() can be called for an existing reused ifa, then,
this check is always false.

Let's set ifa_dev in inet_alloc_ifa() and remove the check
in inet_set_ifa().

Now, inet_alloc_ifa() is symmetric with inet_rcu_free_ifa().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240809235406.50187-3-kuniyu@amazon.com


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