Fixed some void functions with returns, first stab at cpu ports.

Fixed some void functions with returns, first stab at cpu ports.

cpu/simple/cpu.hh:
    Adding port definitions to simple cpu, still needs work.
mem/bus.hh:
    no return for void functions

--HG--
extra : convert_revision : 42e5bc16af187d3a46eb25a15b600a8a11b88cc5