ARM: OMAP: Move dmtimer driver out of plat-omap to drivers under clocksource

Move the dmtimer driver out of plat-omap to clocksource.
So that non-omap devices also could use this.

No Code changes done to the driver file only renamed to timer-ti-dm.c.
Also removed the config dependencies for OMAP_DM_TIMER.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Tested-by: Ladislav Michl <ladis@linux-mips.org>
[tony@atomide.com: add select omap_dm_timer for omap16xx]
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap1/Kconfig

@@ -30,6 +30,7 @@ config ARCH_OMAP16XX
 	bool "OMAP16xx Based System"
 	select ARCH_OMAP_OTG
 	select CPU_ARM926T
+	select OMAP_DM_TIMER
 
 config OMAP_MUX
 	bool "OMAP multiplexing support"