feat(spmd): add spmd logical partitions

Add header file to help with creation of SPMD logical partitions. Also
update linker files to create sections to record SPMD logical partitions
declared. This follows the same pattern as the EL3 SPMC's logical
partitions. This patch also adds initialization of SPMD logical
partitions when the SPMD comes up.
ENABLE_SPMD_LP is a build flag that is used to enable support for
SPMD logical partitions.
Note that the approach chosen is to keep SPMD and SPMC logical
partition support separate, as opposed to extend the existing SPMC
logical partition support since the code would need to have a number of
ifdefs and the interactions with various build options such as
SPMC_AT_EL3 needs to be accounted for, which would make code more
complicated.

Signed-off-by: Raghu Krishnamurthy <raghu.ncstate@gmail.com>
Change-Id: I9642ddbf6ea26dd3f4a283baec598d61c07e3661
8 files changed