net/mlx5: Move IRQ rmap creation to IRQ allocation phase

Rmap creation/deletion is part of the IRQ life-cycle.

Signed-off-by: Yuval Avnery <yuvalav@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>