UPSTREAM: af_unix: Return struct unix_sock from unix_get_socket().

commit 5b17307b upstream.

Currently, unix_get_socket() returns struct sock, but after calling
it, we always cast it to unix_sk().

Let's return struct unix_sock from unix_get_socket().

Bug: 404256079
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240123170856.41348-4-kuniyu@amazon.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 7637a75a)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Ideebd80d54cd27e6ef67edc1305228d28e3a70e6