OMAP3: PM: Allow the cache clean when L1 is lost.

When L1 cache is suppose to be lost, it needs to be cleaned before
entrering to the low power mode.

While at this, also fix few comments and remove un-necessary
clean_l2 lable.

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