sched: don't use preprocessor directives inside a macro

The preprocessor directives are used inside sched_enq_deq_task
trace point which is a macro. This is forbidden and sparse gives
an error. To fix this, we always print the task walt stats in this
trace point. When WALT is not enabled, the stats are printed as 0.

Change-Id: Ibe3460e7c22b85220c2088da4570c2c9fd03c848
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>