usb: gadget: udc: Remove USB_GADGET_DUALSPEED select

USB_GADGET_DUALSPEED was removed by commit 85b8614d ("usb: gadget:
get rid of USB_GADGET_{DUAL,SUPER}SPEED"), but the USB_SNP_UDC_PLAT
symbol still selects it.

Remove the USB_GADGET_DUALSPEED select from USB_SNP_UDC_PLAT.

Discovered with the
https://github.com/ulfalizer/Kconfiglib/blob/master/examples/list_undefined.py
script.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/Kconfig

@@ -274,7 +274,6 @@ config USB_SNP_UDC_PLAT
 	tristate "Synopsys USB 2.0 Device controller"
 	depends on USB_GADGET && OF && HAS_DMA
 	depends on EXTCON || EXTCON=n
-	select USB_GADGET_DUALSPEED
 	select USB_SNP_CORE
 	default ARCH_BCM_IPROC
 	help