tbbr/dualroot: rename SP package certificate file ...

Currently only single signing domain is supported for SP packages but
there is plan to support dual signing domains if CoT is dualroot.

SP_CONTENT_CERT_ID is the certificate file which is currently generated
and signed with trusted world key which in-turn is derived from Silicon
provider RoT key.
To allow dual signing domain for SP packages, other certificate file
will be derived from Platform owned RoT key.

This patch renames "SP_CONTENT_CERT_ID" to "SIP_SP_CONTENT_CERT_ID" and
does other related changes.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I0bc445a3ab257e2dac03faa64f46e36a9fed5e93

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