enable dummy-hcd as workaround for libusb bug

libusb crashes (SEGV) on some functions when no USB controller is present. This
results in annoying ABRT popup about colord-sane crash.
Enable dummy USB controller to suppress this bug. This can be reverted when we
enable (some type of) PVUSB in each domain by default.

config-pvops

@@ -4389,6 +4389,7 @@ CONFIG_USB_SL811_CS=m
 CONFIG_USB_R8A66597_HCD=m
 CONFIG_USB_WHCI_HCD=m
 CONFIG_USB_HWA_HCD=m
+# CONFIG_USB_RENESAS_USBHS is not set
 
 #
 # USB Device Class drivers
@@ -4518,7 +4519,42 @@ CONFIG_USB_SPEEDTOUCH=m
 CONFIG_USB_CXACRU=m
 CONFIG_USB_UEAGLEATM=m
 CONFIG_USB_XUSBATM=m
-# CONFIG_USB_GADGET is not set
+CONFIG_USB_GADGET=m
+# CONFIG_USB_GADGET_DEBUG is not set
+# CONFIG_USB_GADGET_DEBUG_FILES is not set
+# CONFIG_USB_GADGET_DEBUG_FS is not set
+CONFIG_USB_GADGET_VBUS_DRAW=2
+CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS=2
+# CONFIG_USB_R8A66597 is not set
+# CONFIG_USB_GADGET_DWC3 is not set
+# CONFIG_USB_M66592 is not set
+# CONFIG_USB_AMD5536UDC is not set
+# CONFIG_USB_CI13XXX_PCI is not set
+# CONFIG_USB_NET2272 is not set
+# CONFIG_USB_NET2280 is not set
+# CONFIG_USB_GOKU is not set
+# CONFIG_USB_EG20T is not set
+CONFIG_USB_DUMMY_HCD=m
+CONFIG_USB_GADGET_DUALSPEED=y
+CONFIG_USB_GADGET_SUPERSPEED=y
+# CONFIG_USB_ZERO is not set
+# CONFIG_USB_AUDIO is not set
+# CONFIG_USB_ETH is not set
+# CONFIG_USB_G_NCM is not set
+# CONFIG_USB_GADGETFS is not set
+# CONFIG_USB_FUNCTIONFS is not set
+# CONFIG_USB_FILE_STORAGE is not set
+# CONFIG_USB_MASS_STORAGE is not set
+# CONFIG_USB_G_SERIAL is not set
+# CONFIG_USB_MIDI_GADGET is not set
+# CONFIG_USB_G_PRINTER is not set
+# CONFIG_USB_CDC_COMPOSITE is not set
+# CONFIG_USB_G_NOKIA is not set
+# CONFIG_USB_G_ACM_MS is not set
+# CONFIG_USB_G_MULTI is not set
+# CONFIG_USB_G_HID is not set
+# CONFIG_USB_G_DBGP is not set
+# CONFIG_USB_G_WEBCAM is not set
 
 #
 # OTG and related infrastructure