net/mlx5: HWS, Fix memory leak in hws_pool_buddy_init error path

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

net/mlx5: HWS, Fix memory leak in hws_pool_buddy_init error path

In the error path of hws_pool_buddy_init(), the buddy allocator cleanup doesn't free the allocator structure itself, causing a memory leak.

Add the missing kfree() to properly release all allocated memory.