From: Adrian Bunk <bunk@fs.tum.de>

four months ago, Rolf Eike Beer <eike-kernel@sf-tec.de> sent a patch
against 2.6.0-test5-bk1 that converted several if ...  BUG() to BUG_ON()

This might in some cases result in slightly faster code because BUG_ON()
uses unlikely().