net/mlx5e: Fix mapping of ct_label zero

ct_label 0 is a default label each flow has and therefore
there can be rules that match on ct_label=0 without a prior
rule that set the ct_label to this value.

The ct_label value is not used directly in the HW rules and
instead it is mapped to some id within a defined range and this
id is used to set and match the metadata register which carries
the ct_label.

If we have a rule that matches on ct_label=0, the hw rule will
perform matching on a value that is != 0 because of the mapping
from label to id. Since the metadata register default value is
0 and it was never set before to anything else by an action that
sets the ct_label, there will always be a mismatch between that
register and the value in the rule.

To support such rule, a forced mapping of ct_label 0 to id=0
is done so that it will match the metadata register default
value of 0.

Fixes: 54b154ec ("net/mlx5e: CT: Map 128 bits labels to 32 bit map ID")
Signed-off-by: Ariel Levkovich <lariel@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>