Updated size values, added be signal, added attr signal, allowed (som…

Created by: Silabs-ArjanB

…etimes mandated) coprocessor to modify transactions

This change is not backward compatible as the coprocessor is now mandated to split transactions that cross the X_MEM_WIDTH boundary. Allowing (and sometimes mandating) a coprocessor to split (or more generally modify) transactions provides a significant performance increase for the scenario of for example a vector processor performing a series of unaligned address consecutive transactions. (The splitting then needs to be done once for the series instead of per transaction in the series).

This PR is aimed at addressing the issues mentioned in https://github.com/openhwgroup/core-v-xif/issues/17.

Signed-off-by: Arjan Bink Arjan.Bink@silabs.com