ARM: dts: msm: schedule mmcqd on idle CPU on 8992 and 8994

In order to boost mmc performance on 8992 and 8994,
configure wakeup-on-idle. This will cause the mmc queue
thread (mmcqd) to be scheduled on an idle CPU.

CRs-Fixed: 787554
Change-Id: Iaebfa2ac5f2449e645b5a77ecc34532566f87706
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>