ARM: dts: msm: Add TCSR_USB_PHY_VLS_CLAMP reg offset for sdxpoorwills

vls clamp needs to be enabled/disabled when enabling/disabling phy
autonomous mode. This is mandatory property for QMP PHY not supporting
display port. Hence probe would fail if it is not defined.

Change-Id: Ibac08ec743872ce4679255bb693cfea3eedd7c88
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>