vhost: use kzalloc() instead of kmalloc() followed by memset()

commit 4d8df0f5 upstream.

Use kzalloc() to allocate new zeroed out msg node instead of
memsetting a node allocated with kmalloc().

Signed-off-by: Prathu Baronia <prathubaronia2011@gmail.com>
Message-Id: <20230522085019.42914-1-prathubaronia2011@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Ajay Kaher <ajay.kaher@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>