usb: add a flag to skip PHY initialization to struct usb_hcd

The USB HCD core driver parses the device-tree node for "phys" and
"usb-phys" properties. It also manages the power state of these PHYs
automatically.
However, drivers may opt-out of this behavior by setting "phy" or
"usb_phy" in struct usb_hcd to a non-null value. An example where this
is required is the "Qualcomm USB2 controller", implemented by the
chipidea driver. The hardware requires that the PHY is only powered on
after the "reset completed" event from the controller is received.

A follow-up patch will allow the USB HCD core driver to manage more than
one PHY. Add a new "skip_phy_initialization" bitflag to struct usb_hcd
so drivers can opt-out of any PHY management provided by the USB HCD
core driver.

This also updates the existing drivers so they use the new flag if they
want to opt out of the PHY management provided by the USB HCD core
driver. This means that for these drivers the new "multiple PHY"
handling (which will be added in a follow-up patch) will be disabled as
well.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Peter Chen <peter.chen@nxp.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.con>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>