hwrng: timeriomem - Use phys address rather than virt

There is no ioremap'ing or anything in timeriomem-rng.c as I foolishly
used already remapped virtual addresses instead of passing the physical
address to be polled.

This patch fixes this flaw and lets developers do the Right Thing(tm).

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>