ARM: 7081/1: mach-integrator: fix the clocksource

I was intrigued by the fact that the clock stood still on
the Integrator, but it wasn't strange at all, because the
timer was set up all wrong and probably has been for a
while. With this patch the clock starts ticking again:
make the timer periodic (reload), |= on the divisor bit
and load the timer before starting it.

Cc: stable@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>