dts: Add CoT descriptor nodes and properties in device tree ...

Added CoT descriptor nodes and properties in device tree.
Currently, CoT descriptors which are used by BL2 are added as part
of device tree.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Iff23cff843e5489fac18bcee5f5d6a71de5ad0d0