The XIP SPI flash on Fomu is slow, which results in certain operations
taking a long time. This becomes a problem for time-critical operations
such as USB.
Move various calls into RAM to improve performance.
This includes the call to __modsi3 and __udivsi3 which are used by the
supervisor handler to determine if periodic callbacks need to be run.
This finishes fixing #3841
Signed-off-by: Sean Cross <sean@xobs.io>
