ARM: sun8i: a83t: cubietruck-plus: Enable onboard USB peripherals

The Cubietruck-plus has a GL830 USB-to-SATA bridge connected to EHCI0,
and a USB3503 HSIC USB 2.0 hub connected to EHCI1. The USB3503's I2C
control interface is not connected.

This patch enables both EHCI controllers, adds a device node for the
USB hub, and includes sunxi-common-regulators.dtsi for the VBUS
regulators. The existing reg_vcc3v3 is dropped as it is also available
in the set of common regulators. Other unused regulators are disabled.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>