On the Optimus board, all three USB hosts can be used.
HCI0 and HCI2 are available through the USB connector.
HCI1 is available with HSIC through 2 pins on the GPIO
expansion header.

This patch also adds a regulator for HCI2/USB3's VBUS.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>