cpu-target: Include missing 'exec/memory.h' header

Include "exec/memory.h" in order to avoid:

  cpu-target.c:201:50: error: use of undeclared identifier 'TYPE_MEMORY_REGION'
      DEFINE_PROP_LINK("memory", CPUState, memory, TYPE_MEMORY_REGION,
                                                   ^

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

cpu-target.c

@@ -31,6 +31,7 @@
 #else
 #include "hw/core/sysemu-cpu-ops.h"
 #include "exec/address-spaces.h"
+#include "exec/memory.h"
 #endif
 #include "sysemu/cpus.h"
 #include "sysemu/tcg.h"