ARM: dts: remove unused gpio from mdss for 8909 CDP

In 8909 cdp mdss accesses gpio 97 which is not needed.
Avoid this so that other subsystems requiring it can
get control of it.

Change-Id: I28ef292ce2e3ceb154f3d9d9c56ed9ee02d899bf
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>