disas.c: Use address_space_read() to read memory

disas.c: Use address_space_read() to read memory

Currently disas.c reads physical memory using
cpu_physical_memory_read(). This effectively hard-codes
assuming that all CPUs have the same view of physical
memory. Switch to address_space_read() instead, which
lets us use the AddressSpace for the CPU we're
disassembling for.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20181122172653.3413-2-peter.maydell@linaro.org