OMAP3: CPUidle: remove redundant setting of PER next power state

When checking how to program the next powerstate for the PER
powerdomain, the next state of PER powerdomain was written twice.
Remove the duplicate write.

Reported-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>