Update the CMT clockevent rating from 125 to 80.

This resolves a boot-failure regression for kzm9g-reference in v3.10-rc1
introduced by f7db706b ("ARM: 7674/1: smp:
Avoid dummy clockevent being preferred over real").

The patch noted above reduces the rating of dummy clockevent from 400 to 100.
This patch reduces the rating of CMT so that it is once again less than that
of the dummy clockevent.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>