net/mlx5e: SHAMPO, Change frag page setup order during allocation

Now that the UMR allocation has been simplified, it is no longer
possible to have a leftover page from a previous call to
mlx5e_build_shampo_hd_umr().

This patch simplifies the code by switching the order of operations:
first take the frag page and then increment the index. This is more
straightforward and it also paves the way for dropping the info
array.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20241107194357.683732-11-tariqt@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>