fwk: Add support for static element tables

Element tables are always expected to be generated at module
initialization time. Most modules, however, can provide these elements
at compile-time. This commit adds support for doing so.

Change-Id: I77c64ddcb6e406cc1eecbf60f1d6b817384ae4f8
Signed-off-by: Chris Kay <chris.kay@arm.com>