Update PLIC register map.

The secure core's PLIC was updated to the RISC-V standard. This means
moving register locations around.

Update constants with latest info:
./hw/opentitan-upstream/util/regtool.py -R -o /usr/local/google/home/jesionowski/shodan/sw/matcha/hal/src/plic_constants.rs ./hw/opentitan-upstream/hw/top_matcha/ip_autogen/rv_plic/data/rv_plic.hjson

Interrupt source was removed, so remove reference to those registers.

The security core shouldn't refer to the SMC's PLIC, removed reference.
This breaks an unused function, added TODO for Austin.

Change-Id: If0758f222982127016b4faa72d36a56400773991
4 files changed