net/mlx5e: Add logic to read RS-FEC histogram bin ranges from PPHCR

Introduce support for querying the Ports Phy Histogram Configuration
Register (PPHCR) to retrieve RS-FEC histogram bin ranges. The ranges
are stored in a static array and will be used to map histogram counters
to error levels.

The actual RS-FEC histogram statistics are not yet reported in this
commit and will be handled in a downstream patch.

Co-developed-by: Yael Chemla <ychemla@nvidia.com>
Signed-off-by: Yael Chemla <ychemla@nvidia.com>
Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Yael Chemla <ychemla@nvidia.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Link: https://patch.msgid.link/20250924124037.1508846-4-vadim.fedorenko@linux.dev


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