ARM: dts: msm: Support mini DP on SM6150 IDP

Add the gpio setting which acts as hpd for DP in the absence of usbpd.

Change-Id: I2904a1fcc42d06af970367c119c81a93fcf4d40e
Signed-off-by: Sankeerth Billakanti <sbillaka@codeaurora.org>