engine: [Fix] Remove HotPlugUnsupportedOsList config value

The property HotPlugUnsupportedOsList was remove after the migration to
the osinfo file, but the name is wrong in this script.

Change-Id: I67a79cff58983540fa22b60501c5d390a3972b2a
Signed-off-by: Gustavo Pedrosa <gustavo.pedrosa@eldorado.org.br>