kernel: add user data API to timers

Similar to what was available with nano timers in the original kernel,
allow a user to associate opaque data with a timer.

Fix for ZEP-1558.

Change-Id: Ib8cf998b47988da27eba4ee5cd2658f90366b1e4
Signed-off-by: Benjamin Walsh <walsh.benj@gmail.com>
4 files changed