defconfig: arm: disable sched_debug for sdxlemur

CONFIG_SCHED_DEBUG maintains scheduler statistic debug information
and can accessed the data dynamically.

On user builds, its not needed to enable debug related information,
so disable the scheduler debug.

Change-Id: I5b5b14e1bd1498945bbbd67d797330e9cdcc17bd
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>