ARM: dts: msm: Disable ethernet interface for mhi swip for sdxpoorwills

Remove "qcom,mhi-ethernet-interface" property such that mhi swip
will support default rawip network interface instead of ethernet
network interface on sdxpoorwills.

Change-Id: Ic0a4c0e5177a0258b26c66802ed14278eeec258f
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>