mlxsw: Support configuring 'max_lag' via CONFIG_PROFILE

In the device, LAG identifiers are stored in the port group table (PGT).
During initialization, firmware reserves a certain amount of entries at
the beginning of this table for LAG identifiers.

In Spectrum-4, the size of the PGT table did not increase, but the maximum
number of LAG identifiers was doubled, leaving less room for others entries
(e.g., flood entries) that also reside in the PGT.

Therefore, in order to avoid a regression and as long as there is no
explicit requirement to support 256 LAGs, mlxsw driver will configure the
firmware to allocate the same amount of LAG entries (128) as in
Spectrum-{2,3}. This configuration is done using 'max_lag' field in
CONFIG_PROFILE command. Extend 'struct mlxsw_config_profile' to support
'max_lag' field and configure firmware accordingly.

A next patch will adjust Spectrum-4 to configure 'max_lag' field.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>