lib: fconf: Implement a parser to populate CoT ...

Implemented a parser which populates the properties of
the CoT descriptors as per the binding document [1].
'COT_DESC_IN_DTB' build option is disabled by default and can
be enabled in future for all Arm platforms by making necessary
changes in the memory map.
Currently, this parser is tested only for FVP platform.

[1]:
https://trustedfirmware-a.readthedocs.io/en/latest/components/cot-binding.html

Change-Id: I2f911206087a1a2942aa728de151d2ac269d27cc
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>