OMAP4: PM: TWL6030: fix ON/RET/OFF voltages

According to latest OMAP4430 Data Manual v0.4 dated March 2011:
 - Retention voltage shall be set to 0.83V. See tables 2.2, 2.4 and 2.6 in DM.
   This allows saving a little more power in retention states.
 - OPP100 IVA nominal voltage is 1.188V. See table 2.4 in DM.
   This allows saving a little power when CPU wakes up until Smart-Reflex is
   not yet resumed.

[nm@ti.com: ported to voltdm_c]
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Patrick Titiano <p-titiano@ti.com>