ARM: dts: msm: add active display flag to proper node for sdm670

Currently active display flag is added in panel dtsi file.
But the correct place to add this flag is display dtsi file.
This change fixes the same for sdm670 platform.

Change-Id: I8b36deff4dc4c0001083efd057fb0b6a27c229d2
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>