ksmbd: Fix potential memory leak in tcp_destroy_socket()

ksmbd_socket must be freed even if kernel_sock_shutdown() somehow fails.

Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>