ARM: dts: qcom: sdx55-fn980: Mark ico and efs2 partitions as secure

On Telit FN980 TLB, "ico" and "efs2" NAND partitions are secured by
Trustzone. So let's mark them as secure by passing the offset and size
using "qcom,secure-regions" property. This will make sure that the
driver will skip read/write access to these regions.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>