ARM: dts: msm: add MDSS DP device node for msmcobalt

Add MDSS Display-Port device node for msmcobalt which is needed to drive
any external display that supports DP interface. Add the
msmcobalt-CDP/MTP specific GPIO entries needed for display-port.

Change-Id: I61592c167345ebec4cde07f0a72ef059f186b84a
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>