net/mlx5: E-switch, Set per vport table default group number

Different per voprt table is created using a different per vport table
namespace. Because we can't use variable to set the namespace member
value.  If max group number is 0 in the namespace, use the eswitch
default max group number.

Signed-off-by: Chris Mi <cmi@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>