Add clocksource driver for OMAP1.

Signed-off-by: Dirk Behme <dirk.behme_at_gmail.com>

What do you think about this? OSK still boots and I can't
see any runtime issues. But maybe others?

For reference see

- The two new files highres.txt and hrtimers.txt in
http://tglx.de/projects/hrtimers/2.6.18/patch-2.6.18-hrt-dyntick2.patch
- 
http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036695.html 

(and the other "clocksource" patches there)
- 
http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036713.html

Next steps would be:

* Move omap_clocksource_init() to something like

http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036700.html

* Add clockevent system, e.g.

http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036705.html

(and the other "clockevent" patches there)

* Enable generic time and generic clock events:

http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036696.html
http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036711.html

But seems that we have to wait some integration cylces
of mainline for this.

Cheers

Dirk

Btw: With clocksource added, we should be able to use
rt-preempt patch:

http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-October/036496.html
rt.wiki.kernel.org
http://www.linuxdevices.com/news/NS9566944929.html

if it will be available for 2.6.19 (with some small OMAP
specific adaptions) .