ARM: dts: msm: enable battery detect for flash LED

Flash LED current gets clamped by PMIC when battery level is low.
This brings very bad user experience and even PMIC reset. This
feature enables flash LED query maximum LED intensity at current
battery level to avoid clamp or PMIC reset.

CRs-Fixed: 668751
Change-Id: Icafb11a6e8d22dcdd8fd646dca6cbfffe1dc77b4
Signed-off-by: Chun Zhang <chunz@codeaurora.org>