usb: gadget: fsl_qe_udc: convert to new style start/stop

This patches converts the driver into the new style start/stop interface.
As a result the driver no longer uses the static global udc_conroller variable.
Compile tested only.

Cc: Li Yang <leoli@freescale.com>
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Felipe Balbi <balbi@ti.com>