ice40: Generate sdf file from icestorm `*` entries
ice40: Generate sdf file from icestorm `*` entries

Signed-off-by: Elms <23ce84ca7a7de9dc17ad8e8b0bbd717d4f9f9884@freshred.net>

SymbiFlow/symbiflow-arch-defs,SymbiFlow/symbiflow-arch-defs