defconfig: msm8939: enable SCHED_HMP

The msm8939 target has a heterogeneous CPU topology.
Support that topology in the scheduler with SCHED_HMP.

Change-Id: I9f10131d322d1bb599145f07dd507a7b9c8572dc
Signed-off-by: Hanumath Prasad <hpprasad@codeaurora.org>