usb: remove redundant dependency on USB_SUPPORT

The whole Kconfig entries of the USB subsystem are surrounded with
"if USB_SUPPORT" ... "endif", so CONFIG_USB_SUPPORT=y is surely met
when these two Kconfig options are visible.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>