scripts/dump-guest-memory: Synchronize with guest_phys_blocks_region_add

Recent patches have removed ram_device and nonvolatile RAM
from dump-guest-memory's output.  Do the same for dumps
that are extracted from a QEMU core file.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/dump-guest-memory.py

@@ -417,7 +417,9 @@ def get_guest_phys_blocks():
         memory_region = flat_range["mr"].dereference()
 
         # we only care about RAM
-        if not memory_region["ram"]:
+        if (not memory_region["ram"] or
+            memory_region["ram_device"] or
+            memory_region["nonvolatile"]):
             continue
 
         section_size = int128_get64(flat_range["addr"]["size"])