net/mlx5e: Fix hairpin RSS table size

Set hairpin table size to the corret size, based on the groups that
would be created in it. Groups are laid out on the table such that a
group occupies a range of entries in the table. This implies that the
group ranges should have correspondence to the table they are laid upon.

The patch cited below  made group 1's size to grow hence causing
overflow of group range laid on the table.

Fixes: a795d8db

 ("net/mlx5e: Support RSS for IP-in-IP and IPv6 tunneled packets")
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>