usb: dwc2: gadget: Add DMA descriptor chains for EP 0

Update dwc2_hsotg structure to add descriptor chains for EP 0: two DMA
descriptors for Setup phase, per one for IN/OUT data and status phases.
Add their allocation function dwc2_gadget_alloc_ctrl_desc_chains() and
its call during gadget probe.

Signed-off-by: Vahram Aharonyan <vahrama@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>