The two most significant bits of the "local_port" field in the SSPR
register are always cleared since they are overwritten by the deprecated
and overlapping "sub_port" field.

On systems with more than 255 local ports (e.g., Spectrum-4), this
results in the firmware maintaining invalid mappings between system port
and local port. Specifically, two different systems ports (0x1 and
0x101) point to the same local port (0x1), which eventually leads to
firmware errors.

Fix by removing the deprecated "sub_port" field.

Fixes: fd24b29a ("mlxsw: reg: Align existing registers to use extended local_port field")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/9b909a3033c8d3d6f67f237306bef4411c5e6ae4.1692268427.git.petrm@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>