ARM: dts: msm: fix DTP8996 static display power

i2c_6 is not used on DTP phone which voted aganst XO shutdown
in static display. So disable this unused i2c.

Change-Id: I78bd8878278c972321349e945886c9d0fde5fa33
Signed-off-by: c_wufeng <wufeng.jiang@codeaurora.org>
Signed-off-by: zhengyua <zhengyua@codeaurora.org>