usb: chipidea: add work-around for Marvell HSIC PHY startup

The Marvell 28nm HSIC PHY requires the port to be forced to HS mode after
the port power is applied. This is done using the test mode in the PORTSC
register.

As HSIC is always HS, this work-around should be safe to do with all HSIC
PHYs and has been tested on i.MX6S.

Signed-off-by: Rob Herring <robh@kernel.org>
Tested-by: Peter Chen <Peter.Chen@freescale.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>