ARM: dts: msm: Disable USB GPIO detection for SDX20 MTP

Currently, SDX20 MTP uses both SMB and GPIO based detection,
which leads the USB and SMB interfering with each other
and hence ending up mis-detecting the charger type.
Remove the GPIO based detection as SDX20 MTP is expected
to use SMB for charger detection.

Change-Id: I7f541303adacf100672c0587d907fa6a26ce1abd
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>