ARM: dts: msm: Add new bus scaling entry for usb3 node

commit f0d6bd14 ("usb: dwc3-msm: Add dynamic pm_qos, clock and bus
voting in host mode") added changes in DWC3 driver to use three bus
scaling votes. With this driver mandates to have three votes in DT node.
Hence add new bus scaling entry for usb3 device node.

Change-Id: I22bdd37477f9050b5c330f41436b3ec2ac791fd6
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>