net/mlx5e: Use multiple CQ doorbells

Channel doorbells are now also used by all channel CQs.

A new 'uar' parameter is added to 'struct mlx5e_create_cq_param',
which is then used in mlx5e_alloc_cq.

A single UAR page has two TX doorbells and a single CQ doorbell, so
every consecutive pair of 'struct mlx5_sq_bfreg' (TX doorbells)
uses the same underlying 'struct mlx5_uars_page' (CQ doorbell).
So by using c->bfreg->up, CQs from every consecutive channel pair will
share the same CQ doorbell.

Non-channel associated CQs keep using the global CQ doorbell.

Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>