OMAP: omap_device: make latency autoadjust messages debug

During normal system operation warning messages similar to this
are appearing quite often:
omap_device: omap4-keypad.-1: new worst case activate latency 0: 61035

This doesn't seem to be reporting a problem, nor is it very useful for
non-developers, so reduce it to debug level.

Acked-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>