Added support for changing the core (GPU) and IVA voltages.
The mutex 'omap_dvfs_lock' is also locked when changing the MPU,
core or IVA voltages to prevent requested GPU and IVA OPP changes
from interfering.
Properly account for the possibility of several frequencies having the
same voltage dependency. When changing the core voltages the voltage
dependencies in the OPP of L3, GPU, FDIF and HSI are adjusted. When
changing the IVA voltages the voltage dependencies in the OPP of IVA,
DSP and AESS are adjusted.