USB: Remove last bit of CONFIG_USB_BERRY_CHARGE

One last bit was missed while removing the USB_BERRY_CHARGE config
option in a8d4211f which gets dropped
by this patch.

Signed-off-by: Christoph Egger <siccegge@stud.informatik.uni-erlangen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>