nfp: xsk: Adjust allocation type for nn->dp.xsk_pools

nfp: xsk: Adjust allocation type for nn->dp.xsk_pools

In preparation for making the kmalloc family of allocators type aware,
we need to make sure that the returned type from the allocation matches
the type of the variable being assigned. (Before, the allocator would
always return "void *", which can be implicitly cast to any pointer type.)

The assigned type "struct xsk_buff_pool **", but the returned type will be
"struct xsk_buff_pool ***". These are the same allocation size (pointer
size), but the types don't match. Adjust the allocation type to match
the assignment.

Signed-off-by: Kees Cook <kees@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250426060841.work.016-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>