defconfig: Enable CONFIG_SCHED_DEBUG and CONFIG_SCHEDSTATS

CONFIG_SCHED_DEBUG and CONFIG_SCHEDSTATS provide useful information to
debug scheduler issues. Enable these options for debug builds.
CONFIG_SCHED_DEBUG adds very minimal overhead, and that too, only when user
attempts to read some files in /proc. CONFIG_SCHEDSTATS maintains execution
statistics for all tasks on a ongoing basis and will have very minimal
overhead. The execution statistics help understand (among other things)
tasks having large scheduling latencies and thus lead to performance
issues.

Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Change-Id: Ia4547015925a50829685c75ac6b8fc291b06cc6a