OMAP5: audit dpll should audit at the right OPP

Originally, when do omapconf-audit-dpll it will just audit DPLL
settings at current MPU OPP for 4 times, but not in 4 different OPPs.

Fix the same so that it will successfully audit DPLL settings in OPP
low, nom, high, and speedbin.

Signed-off-by: Jin Zheng <j-zheng@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>