Next steps for pulp_cluster

[luca-valente]

Hi everyone,
writing here 2 new possible targets to discuss for the pulp_cluster:

1. Add support for OpenHardware's cv32e40p with 32-bit Instruction Cache.
2. Connect the s_core_instr_bus directly to the SoC (@meggiman @bluewww) as an additional axi master.

While I believe we'll all agree that number 1 is necessary, number 2 may need some discussion, as it also needs changes on Pulp SoC. In the meantime, I will start working on number 1.