arm64: dts: renesas: salvator-common: add companion property in usb3_peri0

This patch adds a property "companion" with xhci0 phandle to
the usb3_peri0 node in salvator-common.dtsi.

About the detail of this property for renesas_usb3 udc driver, please
refer to the commit 39facfa0 ("usb: gadget: udc: renesas_usb3:
Add register of usb role switch").

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>