hw/hppa: Change fw_cfg port address

hw/hppa: Change fw_cfg port address

Devices on hppa occupy at least 4k starting at the HPA, so MEMORY_HPA+4k is
blocked (by Linux) for the memory module.  I noticed this when testing the new
Linux kernel patch to let the fw_cfg entries show up in Linux under /proc.
The Linux kernel driver could not allocate the region for fw_cfg.
This new base address seems to not conflict.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>