usb: phy: omap: Add new device types and remove omap_control_usb3_phy_power()

Add support for new device types and in the process rid of "ti,type"
device tree property. The correct type of device will be determined
from the compatible string instead.

Introduce a compatible string for each device type. At the moment
we support 4 types OTGHS, USB2, PIPE3 (e.g. USB3) and DRA7USB2.

Update DT binding information to reflect these changes.

Also get rid of omap_control_usb3_phy_power(). Just one function
i.e. omap_control_usb_phy_power() will now take care of all PHY types.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>