IB/mlx5: Fix atomic cap in indirect UMR

Remove from the driver the limitation imposed by firmware check
to not allow change of atomic permissions for indirect UMRs.
In order to avoid failures on old firmware, we only ask for change
of atomic permissions if atomic operations are supported.

Fixes: 968e78dd ('IB/mlx5: Enhance UMR support to allow partial page table update')
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>