usb: phy-zynq: Enable Vbus if port A is detected.

With the current implementation, A-device can only provide Vbus to
B-device through sysfs attribute "a_bus_req".
So, modified the driver to enable Vbus if port A is detected so that
with out userspace help the vbus can be provided to the B-device.

Signed-off-by: Punnaiah Choudary Kalluri <punnaia@xilinx.com>
Tested-by: Mike Looijmans <mike.looijmans@topic.nl>
zynq usb: Allow use of external VBUS regulator

Add support for driving an external VBUS regulator. This makes it possible
to operate the USB in OTG mode without requiring programmable logic to drive
the VBUS controls, such as a MIO GPIO pin or external I2C regulator.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
dts/topic-miami: Add OTG mode for USB

The USB port will automatically switch between host and peripheral mode
depending on the plug inserted. A micro-B plug will select peripheral
mode and set up a network link with the host on the other side. A micro-A
plug will enable the 5V VBUS power supply and attach a stick or other
gadget. Note that the plug must have the ID pin connected to GND to work
properly in host mode (connect pin 4 and 5), most converter cables do not
have this (they have a micro-B connector).

Tested with a cable that I manually patched to connect pins 4 and 5.
topic-miami-florida.dtsi: Use CDCE925 clock for 12.288MHz SPDIF

Changed logic to obtain the 12.288 MHz sample/bit clock for the
SPDIF interface from the TI CDCE925 clock synthesizer. This can
create the exact frequency for 48kHz audio using a 27MHz XTAL.

Also add an example HDMI pixel clock which may replace the AXI
clockgen for the HDMI output.