Commit caravel RTL changes the caravel_stanford branch of caravel
There are some hand edited files in the RTL node of the caravel mflowgen graph. These need to be propagated into the caravel repo under the caravel_stanford
branch, after making sure that all caravel tests pass.
One of the edits is to remove the PLL, and directly use the clock fed from the I/O. The current code just removes the instantiation, but it would be better to create an `define like USE_PLL to determine whether to instantiate it or not.
A few other edits are related to declaring wires/registers before they are used rather than after.