msm-core: Add additional corner voltage conversion

The driver converts only 4 corner voltages currently.  Add more voltage
conversions to the list.

Note: Remove this after OPP interface provides actual voltage instead of
corner voltage.

Change-Id: Ie7f2792a82aacef8b1594a1069b59da1876a9456
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>