As part of PWM subsystem integration, PWM subsystem are sharing
resources like clock across submodules (ECAP, EQEP & EHRPWM). To handle
resource sharing & IP integration  rework on parent child relation
between PWMSS and ECAP, EQEP & EHRPWM child devices to support runtime PM.
Signed-off-by: NPhilip Avinash <avinashphilip@ti.com>
Signed-off-by: NPaul Walmsley <paul@pwsan.com>