usb: Put USB Kconfig items back under USB.

commit 53c6bc24 (usb: Don't make
USB_ARCH_HAS_{XHCI,OHCI,EHCI} depend on USB_SUPPORT.)  Removed the
dependency of the USB_ARCH_HAS_* symbols on USB_SUPPORT.  However the
resulting Kconfig somehow caused many of the USB configuration items
to appear under the top level devices menu.

To fix this we reunite the 'menuconfig USB_SUPPORT' with the 'if
USB_SUPPORT', and the config items magically go back to their desired
location.

Reported-by: Julian Wollrath <jwollrath@web.de>
Reported-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Reported-by: Rupesh Gujare <rgujare@ozmodevices.com>
Reported-by: Feng King <ronyjin@tencent.com>
Reported-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: David Daney <david.daney@cavium.com>
Tested-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>