Since this is only used internally, and ktime is the basis for
timekeeping in the kernel, this allows this interface to be validated,
before converting the other internal timekeeping to it.
This is part of the changes necessary to remove the use of 'struct
timeval' from the driver suite for compatibility with Linux 5.0, which
is updating the internal timekeeping interfaces to fix the 2038 problem.
Signed-off-by: Shaun Ruffell <sruffell@sruffell.net>
ac50b368aa