hrtimer: fix build bug found by Ingo

in some randconfig configurations, hrtimers are used even though
the hrtimer config if off; and it broke the build due to some of
the new functions being on the wrong side of the ifdef.

This patch moves the functions to the other side of the ifdef, fixing
the build bug.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>