wireguard: peer: Replace sockaddr with sockaddr_inet

As part of the removal of the variably-sized sockaddr for kernel
internals, replace struct sockaddr with sockaddr_inet in the endpoint
union.

No binary changes; the union size remains unchanged due to sockaddr_inet
matching the size of sockaddr_in6.

Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20250722171836.1078436-2-kees@kernel.org


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