sched/fair: Remove the unused code

sysctl_sched_is_big_little is hard coded to 1 and there is
no provision to change it. So find_best_target() path
is never exercised. Remove this unused code. The subsequent
patches make the code under sysctl_sched_is_big_little work
for both big.LITTLE and SMP systems.

Change-Id: I2bd0e121d3c59c58a7c81b2083db6910cce57766
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>