trace/sched: Fix compilation for 32 bit systems

do_div() expects the dividend to be a 64 bit type. We are passing
an unsigned long to do_div() from sched_load_avg_task and
sched_load_avg_cpu trace points. This breaks compilation on
a 32 bit system.

Change-Id: I9eb07dba1e62b68d5fc8d12e3f478b22c4ba5e0d
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>