memory: Fix the memory region type assignment order

memory: Fix the memory region type assignment order

Currently, a callback registered through the RAMBlock notifier
is not able to get the memory region type (i.e callback is not
able to use memory_region_is_ram_device function). This is
because mr->ram assignment happens _after_ the memory is allocated
whereas the callback is executed during allocation.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1667249
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Message-Id: <20190204222322.26766-2-brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>