ARM: OMAP4: PM: Add init api for DPLL nodes

An api at init for all dpll nodes seem to be
needed to reparent the dpll clk node to its
bypass clk in case the dpll is in bypass.
If not done this causes sequencing issues at init
during propogate_rate.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoit Cousson <b-cousson@ti.com>