Draco is a family of 3 boards: thuban, rastaban & etamin. Rename all
targets of the family adding the draco- prefix to increase readibility
and simplify future commits about concerning all boards of the family.
The name draco was initially used for the first target. It's deprecated
since a 2nd target was introduced. Unfortunately the draco target was
copied to the thuban target instead to be renamed. Remove it to save
unnecessary maintenance effort.
Signed-off-by: Enrico Leto <enrico.leto@siemens.com>
