ARM: dts: msm: move led_flash0 device node for msm8974

The device qcom,camera-led-flash (led_flash0) is only used on
msm8974 boards mtp and fluid.  Therefore, move the specification
of this device to camera files that are specific to msm8974-mtp
and msm8974-fluid.

Change-Id: I8813f58546752ae489f46b8d6533e495a3be8db4
Signed-off-by: David Collins <collinsd@codeaurora.org>