memory: Fix type of IOMMUMemoryRegionClass member @parent_class

TYPE_IOMMU_MEMORY_REGION is a direct subtype of TYPE_MEMORY_REGION.
Its instance struct is IOMMUMemoryRegion, and its first member is a
MemoryRegion.  Correct.  Its class struct is IOMMUMemoryRegionClass,
and its first member is a DeviceClass.  Wrong.  Messed up when commit
1221a47467 introduced the QOM type.  It even included hw/qdev-core.h
just for that.

TYPE_MEMORY_REGION doesn't bother to define a class struct.  This is
fine, it simply defaults to its super-type TYPE_OBJECT's class struct
ObjectClass.  Changing IOMMUMemoryRegionClass's first member's type to
ObjectClass would be a minimal fix, if a bit brittle: if
TYPE_MEMORY_REGION ever acquired own class struct, we'd have to update
IOMMUMemoryRegionClass to use it.

Fix it the clean and robust way instead: give TYPE_MEMORY_REGION its
own class struct MemoryRegionClass now, and use it for
IOMMUMemoryRegionClass's first member.

Revert the include of hw/qdev-core.h, and fix the few files that have
come to rely on it.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20190812052359.30071-5-armbru@redhat.com>

include/exec/memory.h

@@ -20,12 +20,12 @@
 #include "exec/hwaddr.h"
 #include "exec/memattrs.h"
 #include "exec/ramlist.h"
+#include "qemu/bswap.h"
 #include "qemu/queue.h"
 #include "qemu/int128.h"
 #include "qemu/notify.h"
 #include "qom/object.h"
 #include "qemu/rcu.h"
-#include "hw/qdev-core.h"
 
 #define RAM_ADDR_INVALID (~(ram_addr_t)0)
 
@@ -205,6 +205,12 @@ struct MemoryRegionOps {
     } impl;
 };
 
+typedef struct MemoryRegionClass {
+    /* private */
+    ObjectClass parent_class;
+} MemoryRegionClass;
+
+
 enum IOMMUMemoryRegionAttr {
     IOMMU_ATTR_SPAPR_TCE_FD
 };
@@ -237,7 +243,7 @@ enum IOMMUMemoryRegionAttr {
  */
 typedef struct IOMMUMemoryRegionClass {
     /* private */
-    struct DeviceClass parent_class;
+    MemoryRegionClass parent_class;
 
     /*
      * Return a TLB entry that contains a given address.