hsl: remove unused hsl_setup function
hsl: remove unused hsl_setup function

This function lives in openBSC not here.

osmocom/libosmo-abis,telenoobie/libosmo-abis,osmobuntu/libosmo-abis,osmobuntu/libosmo-abis,osmobuntu/libosmo-abis,osmocom/libosmo-abis,osmobuntu/libosmo-abis,telenoobie/libosmo-abis,osmocom/libosmo-abis