SPM: Gather memory symbols into one single file

For unified referencing and clearly showcasing SPM required
memory symbols. Memory symbols can come from linker sections,
or be defined in sources with toolchain-specific attributes.

Signed-off-by: Ken Liu <Ken.Liu@arm.com>
Change-Id: I920329ad08c9515e370653a9c5d663f3970b7395
10 files changed