ARM: OMAP: Add dmtimer support for OMAP3

Add DM timer support for OMAP3.

Fixed source clocks for 3430 by Paul Walmsley <paul@pwsan.com>.

Signed-off-by: Syed Mohammed Khasim <x0khasim@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>