net/mlx5: Increase the max number of channels to 128

Currently the max number of channels is limited to 64, which is half of
the indirection table size to allow some flexibility. But on servers
with more than 64 cores, users may want to utilize more queues.

This patch increases the advertised max number of channels to 128 by
changing the ratio between channels and indirection table slots to 1:1.
At the same time, the driver still enable no more than 64 channels at
loading. Users can change it by ethtool afterwards.

Signed-off-by: Fan Li <fanl@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>