OMAP4: Fix bug in omap4460_volts struct

The omap4460_volts struct was incorrectly referencing tps62361
instead of twl6030 as PMIC for the core and mm voltages (the
tps is used for mpu supply only). This shall lead to bad OPP
settings while booting kernel. Fixing it.

Fix some comments as well.

Signed-off-by: Lubomir Popov <lpopov@mm-sol.com>