Allow longer than 18h wakeup delays

The legacy iphb_wait() uses 16-bit integers for specifying the wakeup
ranges and thus effectively limits the maximum wait time to approximately
18 hours.

Since libiphb >= 1.2.0 there has been iphb_wait2() function that allows
using 32-bit integers for wakeup ranges.

Use iphb_wait2() instead of iphb_wait() and update related constants.