tipc: use kfree_sensitive() for aead cleanup

tipc: use kfree_sensitive() for aead cleanup

The tipc_aead_free() function currently uses kfree() to release the aead
structure. However, this structure contains sensitive information, such
as key's SALT value, which should be securely erased from memory to
prevent potential leakage.

To enhance security, replace kfree() with kfree_sensitive() when freeing
the aead structure. This change ensures that sensitive data is explicitly
cleared before memory deallocation, aligning with the approach used in
tipc_aead_init() and adhering to best practices for handling confidential
information.

Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech>
Link: https://patch.msgid.link/20250523114717.4021518-1-zilin@seu.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>