powerpc/configs/6xx: Drop removed CONFIG_USB_LED

In commit a335aaf3 ("usb: misc: remove outdated USB LED driver")
CONFIG_USB_LED was removed, so drop it from our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/ppc6xx_defconfig

@@ -959,7 +959,6 @@ CONFIG_USB_ADUTUX=m
 CONFIG_USB_SEVSEG=m
 CONFIG_USB_LEGOTOWER=m
 CONFIG_USB_LCD=m
-CONFIG_USB_LED=m
 CONFIG_USB_IDMOUSE=m
 CONFIG_USB_FTDI_ELAN=m
 CONFIG_USB_APPLEDISPLAY=m