sh: Fix up clockevents broadcasting.

This fixes up the clockevents broadcasting code as detailed in commit
ee348d5a1d810bc9958cabb7c27302aab235d36e ("[ARM] realview: fix broadcast
tick support"). This saves us from having to do strange ordering things
with the broadcast clockevent device, relying on the rating instead.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>