OMAP: omap_device: use UINT_MAX for default wakeup latency limit

The _dev_wakeup_lat_limit field of struct omap_device is u32, so use
UINT_MAX instead of INT_MAX for the default maximum.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>