usb: gadget: udc: make debug prints compatible with both pci and platform devices

This patch adds a struct device member to UDC data structure and
makes changes to the arguments of dev_err and dev_dbg calls so that
the debug prints work for both pci and platform devices.

Signed-off-by: Raviteja Garimella <raviteja.garimella@broadcom.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>