hw/sd.c: fix migration of dynamically allocated buffer "buf"

VMSTATE_BUFFER_UNSAFE should be used for buffers inlined in device state, not
for buffers allocated dynamically. Change to VMSTATE_BUFFER_POINTER_UNSAFE macro,
which will do migration right.
Signed-off-by: NIgor Mitsyanko <i.mitsyanko@gmail.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Tested-by: NMichael Walle <michael@walle.cc>
Message-id: 1362923278-4080-3-git-send-email-i.mitsyanko@gmail.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/sd.c

@@ -478,7 +478,7 @@ static const VMStateDescription sd_vmstate = {
         VMSTATE_UINT64(data_start, SDState),
         VMSTATE_UINT32(data_offset, SDState),
         VMSTATE_UINT8_ARRAY(data, SDState, 512),
-        VMSTATE_BUFFER_UNSAFE(buf, SDState, 1, 512),
+        VMSTATE_BUFFER_POINTER_UNSAFE(buf, SDState, 1, 512),
         VMSTATE_BOOL(enable, SDState),
         VMSTATE_END_OF_LIST()
     }