OMAP: DSS2: Remove clk optimization at dss init

OMAP: DSS2: Remove clk optimization at dss init

DSS enables core clocks for the duration of initialization to avoid
unnecessary context saves and restores.

With PM runtime the clocks cannot be handled in this way, outside the
dss module drivers. Thus we need to remove the optimization.

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