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

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.

Fixes: c61afff94373 ("net/mlx5: HWS, added memory management handling")
Signed-off-by: Lama Kayal <lkayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Link: https://patch.msgid.link/20250825143435.598584-2-mbloch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>