clocksource: timer-ti-dm: Add support to handle late attach of rproc timers

clocksource: timer-ti-dm: Add support to handle late attach of rproc timers

During late attach, the dmtimers used by remote processors would already
have been configured and running. To prevent the kernel from resetting or
reconfiguring the timers,

- Set the late attach parameter if the timer is already running.
- If late attach flag is set, increment the dmtimer's usage counter
  immediately on probe and maintain this state until remoteproc starts
  the timer. This prevents kernel power management functionality from
  idling and disabling the dmtimers.
- If late attach flag is set, also prevent the dmtimer configuration
  code from modifying the dmtimer registers.

The late attach flag in the omap_dm_timer structure is cleared on timer
start to allow normal operation to resume.

Signed-off-by: Venkateswara Rao Mandela <venkat.mandela@ti.com>
Signed-off-by: Angela Stegmaier <angelabaker@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Shravan Karthik <shravan.karthik@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>