net/mlx5: E-Switch, Prepare to return total vports from eswitch struct

Total vports are already stored during eswitch initialization. Instead
of calculating everytime, read directly from eswitch.

Additionally, host PF's SF vport information is available using
QUERY_HCA_CAP command. It is not available through HCA_CAP of the
eswitch manager PF.
Hence, this patch prepares the return total eswitch vport count from the
existing eswitch struct.

This further helps to keep eswitch port counting macros and logic within
eswitch.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>