ARM: OMAP2+: dmtimer: convert to platform devices

Add routines to converts dmtimers to platform devices. The device data
is obtained from hwmod database of respective platform and is registered
to device model after successful binding to driver.
In addition, capability attribute of each of the timers is added in
hwmod database.

Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Signed-off-by: Thara Gopinath <thara@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Cousson, Benoit <b-cousson@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>