Remove IO_MEM_SUBPAGE

Replace with a MemoryRegion flag.

Signed-off-by: Avi Kivity <avi@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
diff --git a/memory.h b/memory.h
index 77984bb..fbca6f1 100644
--- a/memory.h
+++ b/memory.h
@@ -119,6 +119,7 @@
     void (*destructor)(MemoryRegion *mr);
     ram_addr_t ram_addr;
     IORange iorange;
+    bool subpage;
     bool terminates;
     bool readable;
     bool ram;