Dahdi 2.4.0 not installing dahdi_dummy under REL 5.5

dahdi_dummy module not installed on REL 5.5. Older version of dahdi ( did install the module.

dahdi-dummy isn’t needed with the default configuration for dahdi 2.4.0. If there is no real hardware, which would normally produce the condition for loading dahdi-dummy, dahdi-base.c (the core module) provides timing.