handle_BUG() uses TRAPA_BUG_OPCODE which is only defined for
CONFIG_BUG, make sure it's not built when CONFIG_BUG=n.
Signed-off-by: NNobuhiro Iwamatsu <hemamu@t-base.ne.jp>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>