cmake: mod_smt

This change adds CMake build support for module/smt

Change-Id: I3a846845e243371385df7509c10915454af1d2fc
Signed-off-by: Chris Kay <chris.kay@arm.com>
Signed-off-by: Joel Goddard <joel.goddard@arm.com>
Signed-off-by: Girish Pathak <girish.pathak@arm.com>