ARM: OMAP: Fix clockevent support for hrtimers

One-shot mode was broken in MPU-timer support for OMAP1 due to a typo.

Also, ensure timer is stopped before changing the auto-reload flag.
The TRM says changing the AR flag when timer is running is undefined.

Also set GENERIC_CLOCKEVENTS for all omaps.

Signed-off-by: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>