scripts/dump-guest-memory.py: Make methods functions

The functions dealing with qemu components rarely used parts of the
class, so they were moved out of the class.

As the uintptr_t variable is needed both within and outside the class,
it was made a constant and moved to the top.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Message-Id: <1453464520-3882-3-git-send-email-frankja@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>