mlxsw: port: Edit maximum MTU value

Currently mlxsw driver supports up to 10000 bytes for maximum MTU, this
value is not accurate, we can support up to 10K bytes. Change the value to
the maximum supported MTU by firmware.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/666f51681234aeef09d771833ccb6e94bd323c88.1718275854.git.petrm@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>