[...]

quoted

+enum ena_devlink_param_id {
+      ENA_DEVLINK_PARAM_ID_BASE =

DEVLINK_PARAM_GENERIC_ID_MAX,

quoted

+      ENA_DEVLINK_PARAM_ID_PHC_ENABLE,

What exactly is driver/vendor specific about this? Sounds quite generic to
me.

Can you please clarify the question?
If you refer to the need of ENA_DEVLINK_PARAM_ID_PHC_ENABLE, it was discussed as part of patchset v8 in https://lore.kernel.org/netdev/20250304190504.3743-6-darinzon@amazon.com/ (local)
More specifically in https://lore.kernel.org/netdev/55f9df6241d052a91dfde950af04c70969ea28b2.camel@infradead.org/ (local)