Remove code related to simple next

[ccascone]

The "simple" next table was introduced in fabric-v1model as an alternative to the hashed table for HW targets that did not support action selectors. We do have support for action selectors in TNA so that logic is obsolete and should be removed.

That means removing:

• P4 code wrapped in #ifdef WITH_SIMPLE_NEXT
• Java code that references simple-related tables (look for TODO: add profile with simple next or remove references)