ARM: dts: msm: remove wrong IPA HW mode from 9640

IPA HW modem is set incorrectly to virtual on 9640.
This change removes this setting.

Change-Id: Iaa758eb00bad35125d18f5052ab946c01c1c9755
CRs-Fixed: 1052852
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>