board/omap2plus-cpufreq: add cpu governor change interface
omap2plus: cpufreq: Modify lpj recalculation logic

omap2plus: cpufreq: Modify lpj recalculation logic

Somethimes "mdelay" function provide delay
that several times shorter than it should be.

This happens because recalculating lpj
performed after switching OPP. In this case,
for short period of time, when OPP on MPU
was switched but lpj was not recalculated,
"udelay" function can provide incorrect
delay - upto 5 times shorter
(if OPP was switched from lowest to highest).

This patch changes lpj recalculation logic to:
if OPP will be switched to higher - recalculate lpj before switching OPP,
if OPP will be switched to lower - recalculate lpj after switching OPP.

Change-Id: I3258e756c471fd0258a849d712ab00f4e1279ea9
Signed-off-by: Sergii Postulga <x0153364@ti.com>