OMAPDSS: MANAGER/APPLY: Add runtime_pm protection around wait_for_go/vsync functions

If DSS suspends within the functions dss_mgr_wait_for_go(),
dss_mgr_wait_for_go_ovl() or dss_mgr_wait_for_vsync(). It may lose it's clock
and lead to a register access failure.

Request runtime_pm around these functions.

[archit@ti.com: Moved runtime_pm calls to wait_for_go/vsync functions rather
then calling them from omap_dispc_wait_for_irq_interruptible_timeout()]

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>