ARM: STi: Fix cpu nodes with correct device_type.

This patch fixes cpu nodes with device_type = "cpu". This change was not
necessary before 3.10-rc7.
Without this patch STi SOCs does not boot as SMP.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: Olof Johansson <olof@lixom.net>