CVE-2024-43864: net/mlx5e: Fix CT entry update leaks of modify header context

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5e: Fix CT entry update leaks of modify header context

The cited commit allocates a new modify header to replace the old one when updating CT entry. But if failed to allocate a new one, eg. exceed the max number firmware can support, modify header will be an error pointer that will trigger a panic when deallocating it. And the old modify header point is copied to old attr. When the old attr is freed, the old modify header is lost.

Fix it by restoring the old attr to attr when failed to allocate a new modify header context. So when the CT entry is freed, the right modify header context will be freed. And the panic of accessing error pointer is also fixed.