translate-all.c: memory walker initial address miscalculation

translate-all.c: memory walker initial address miscalculation

The initial base address is miscalculated in walk_memory_regions().
It has to be shifted TARGET_PAGE_BITS more. Holder variables are
extended to target_ulong size otherwise they don't fit for MIPS N32
(a 32-bit ABI with a 64-bit address space) and qemu won't compile.
The issue led to incorrect debug output of memory maps and a
mis-formed coredumped file.

Signed-off-by: Mikhail Ilyin <m.ilin@samsung.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>