replication across each processor type, each handling alignment of
addresses slightly differently.  We unify this mess, and allow for
greater flexibility in the per-CPU architecture TLB handlers.

We also start to remove the ARM cache.h -> cpu_*.h -> proc-fns.h mess
making the code cleaner and easier to follow.

Documentation describing the expected behaviour of each TLB function
for the 32-bit ARM processors is also included.