davinci: da850/omap-l138: unlock PLL registers during init

On omap-l1 devices the PLL registers can be locked from
writes. Currently the cpufreq rate setting code unlocks
PLL0 before the write actually happens. With suspend
support getting added PLL1 registers need be be unlocked
as well.

To facilitate this, unlock both PLLs during the init time
itself.

This also obviates the need to unlock PLL registers for
each CPUFreq transtition.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>