PM: setup initial OPP configuration

pm.c setups the initial voltage and frequencies for init devices
on bootup to be careful of invalid device configurations by
custom bootloaders. However, DVFS data structures are not aware
of these - As a result, when doing the first time scale of
a differnt device we could have a following scenario:

At boot - MPU,IVA,Core at OPP100

after pm framework has completed initialization, lets say IVA/AESS
transitions to OPP50, DVFS framework does not have information about
the OPP current frequency/voltage of IVA/MPU and sees that only
IVA is requested, moves the IVA and core to OPP50. This configuration
is invalid as MPU is currently at OPP100 and device should not have
scaled core to OPP50 without looking at OPP100 configuration of
MPU.

To resolve this, we populate the dvfs data structure with the
requisite init devices' frequency configuration by doing a
omap_device_scale.

Change-Id: Ib3048fb7fadec5adabbbcbce56c1ead026953de6
Reported-by: Hemanth V <hemanthv@ti.com>
Tested-by: Akash Choudhari <akashc@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>