Removed "adding instead of dividing" trick.

Removed "adding instead of dividing" trick.
Caused slowdown in performance instead of speeding up.

src/cpu/base.cc:
    Removed "adding instead of dividing" trick.
src/mem/bus.cc:
    Fixed spelling in comments.
    Removed "adding instead of dividing" trick.

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extra : convert_revision : 65a736f4f09a64e737dc7aeee53b117976330488